diff --git a/build-tests/heft-sass-test/config/sass.json b/build-tests/heft-sass-test/config/sass.json
index bade2384d3c..a4993854d2f 100644
--- a/build-tests/heft-sass-test/config/sass.json
+++ b/build-tests/heft-sass-test/config/sass.json
@@ -9,5 +9,8 @@
   "secondaryGeneratedTsFolders": ["lib"],
   "excludeFiles": ["./ignored1.scss", "ignored2.scss"],
 
+  "fileExtensions": [".module.scss", ".module.sass", ".module.css"],
+  "nonModuleFileExtensions": [".global.scss", ".global.sass", ".global.css"],
+
   "silenceDeprecations": ["mixed-decls", "import", "global-builtin", "color-functions"]
 }
diff --git a/build-tests/heft-sass-test/src/ExampleApp.tsx b/build-tests/heft-sass-test/src/ExampleApp.tsx
index 57f3f692066..5f9e7d817b2 100644
--- a/build-tests/heft-sass-test/src/ExampleApp.tsx
+++ b/build-tests/heft-sass-test/src/ExampleApp.tsx
@@ -3,11 +3,11 @@
 
 import * as React from 'react';
 
-import styles from './styles.sass';
-import oldStyles from './stylesCSS.css';
-import altSyntaxStyles from './stylesAltSyntax.scss';
-import stylesUseSyntax from './stylesUseSyntax.sass';
-import stylesUseAltSyntax from './stylesUseAltSyntax.scss';
+import styles from './styles.module.sass';
+import oldStyles from './stylesCSS.module.css';
+import altSyntaxStyles from './stylesAltSyntax.module.scss';
+import stylesUseSyntax from './stylesUseSyntax.module.sass';
+import stylesUseAltSyntax from './stylesUseAltSyntax.module.scss';
 import './stylesAltSyntax.global.scss';
 
 /**
diff --git a/build-tests/heft-sass-test/src/styles.sass b/build-tests/heft-sass-test/src/styles.module.sass
similarity index 91%
rename from build-tests/heft-sass-test/src/styles.sass
rename to build-tests/heft-sass-test/src/styles.module.sass
index a79830ecfef..61be0178191 100644
--- a/build-tests/heft-sass-test/src/styles.sass
+++ b/build-tests/heft-sass-test/src/styles.module.sass
@@ -1,28 +1,28 @@
-/**
- * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
- * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
- */
-
-// Testing Sass imports
-@import 'stylesImport'
-
-// Testing node_modules imports
-@import '~buttono/buttono'
-
-// Testing root styles
-html, body
-  margin: 0
-  height: 100%
-  background-color: #c0c0c0
-  font-family: Tahoma, sans-serif
-
-// Testing Sass classes
-.exampleApp
-  background-color: #ffffff
-  padding: 20px
-  border-radius: 5px
-  width: 400px
-
-.exampleButton
-  @include buttono-block()
-  @include buttono-style-modifier($background-color: mediumorchid)
+/**
+ * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
+ * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
+ */
+
+// Testing Sass imports
+@import 'stylesImport'
+
+// Testing node_modules imports
+@import 'pkg:buttono/buttono'
+
+// Testing root styles
+html, body
+  margin: 0
+  height: 100%
+  background-color: #c0c0c0
+  font-family: Tahoma, sans-serif
+
+// Testing Sass classes
+.exampleApp
+  background-color: #ffffff
+  padding: 20px
+  border-radius: 5px
+  width: 400px
+
+.exampleButton
+  @include buttono-block()
+  @include buttono-style-modifier($background-color: mediumorchid)
diff --git a/build-tests/heft-sass-test/src/stylesAltSyntax.scss b/build-tests/heft-sass-test/src/stylesAltSyntax.module.scss
similarity index 100%
rename from build-tests/heft-sass-test/src/stylesAltSyntax.scss
rename to build-tests/heft-sass-test/src/stylesAltSyntax.module.scss
diff --git a/build-tests/heft-sass-test/src/stylesCSS.css b/build-tests/heft-sass-test/src/stylesCSS.module.css
similarity index 100%
rename from build-tests/heft-sass-test/src/stylesCSS.css
rename to build-tests/heft-sass-test/src/stylesCSS.module.css
diff --git a/build-tests/heft-sass-test/src/stylesUseAltSyntax.scss b/build-tests/heft-sass-test/src/stylesUseAltSyntax.module.scss
similarity index 100%
rename from build-tests/heft-sass-test/src/stylesUseAltSyntax.scss
rename to build-tests/heft-sass-test/src/stylesUseAltSyntax.module.scss
diff --git a/build-tests/heft-sass-test/src/stylesUseSyntax.sass b/build-tests/heft-sass-test/src/stylesUseSyntax.module.sass
similarity index 100%
rename from build-tests/heft-sass-test/src/stylesUseSyntax.sass
rename to build-tests/heft-sass-test/src/stylesUseSyntax.module.sass
diff --git a/build-tests/heft-sass-test/src/test/__snapshots__/lib-commonjs.test.ts.snap b/build-tests/heft-sass-test/src/test/__snapshots__/lib-commonjs.test.ts.snap
index 6825ac5b4bc..6561952445e 100644
--- a/build-tests/heft-sass-test/src/test/__snapshots__/lib-commonjs.test.ts.snap
+++ b/build-tests/heft-sass-test/src/test/__snapshots__/lib-commonjs.test.ts.snap
@@ -4,14 +4,14 @@ exports[`SASS CJS Shims ignored1.scss: files 1`] = `Array []`;
 
 exports[`SASS CJS Shims ignored2.scss: files 1`] = `Array []`;
 
-exports[`SASS CJS Shims styles.sass: files 1`] = `
+exports[`SASS CJS Shims styles.module.sass: files 1`] = `
 Array [
-  "styles.css",
-  "styles.sass.js",
+  "styles.module.css",
+  "styles.module.sass.js",
 ]
 `;
 
-exports[`SASS CJS Shims styles.sass: styles.css 1`] = `
+exports[`SASS CJS Shims styles.module.sass: styles.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -80,8 +80,8 @@ html, body {
 }"
 `;
 
-exports[`SASS CJS Shims styles.sass: styles.sass.js 1`] = `
-"module.exports = require(\\"./styles.css\\");
+exports[`SASS CJS Shims styles.module.sass: styles.module.sass.js 1`] = `
+"module.exports = require(\\"./styles.module.css\\");
 module.exports.default = module.exports;"
 `;
 
@@ -104,16 +104,14 @@ exports[`SASS CJS Shims stylesAltSyntax.global.scss: stylesAltSyntax.global.css
 
 exports[`SASS CJS Shims stylesAltSyntax.global.scss: stylesAltSyntax.global.scss.js 1`] = `"require(\\"./stylesAltSyntax.global.css\\");"`;
 
-exports[`SASS CJS Shims stylesAltSyntax.scss: files 1`] = `
+exports[`SASS CJS Shims stylesAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesAltSyntax.css",
-  "stylesAltSyntax.global.css",
-  "stylesAltSyntax.global.scss.js",
-  "stylesAltSyntax.scss.js",
+  "stylesAltSyntax.module.css",
+  "stylesAltSyntax.module.scss.js",
 ]
 `;
 
-exports[`SASS CJS Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
+exports[`SASS CJS Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -123,31 +121,19 @@ exports[`SASS CJS Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS CJS Shims stylesAltSyntax.scss: stylesAltSyntax.global.css 1`] = `
-"/**
- * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
- * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
- */
-.ms-label {
-  margin-bottom: 20px;
-}"
-`;
-
-exports[`SASS CJS Shims stylesAltSyntax.scss: stylesAltSyntax.global.scss.js 1`] = `"require(\\"./stylesAltSyntax.global.css\\");"`;
-
-exports[`SASS CJS Shims stylesAltSyntax.scss: stylesAltSyntax.scss.js 1`] = `
-"module.exports = require(\\"./stylesAltSyntax.css\\");
+exports[`SASS CJS Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.scss.js 1`] = `
+"module.exports = require(\\"./stylesAltSyntax.module.css\\");
 module.exports.default = module.exports;"
 `;
 
-exports[`SASS CJS Shims stylesUseAltSyntax.scss: files 1`] = `
+exports[`SASS CJS Shims stylesUseAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesUseAltSyntax.css",
-  "stylesUseAltSyntax.scss.js",
+  "stylesUseAltSyntax.module.css",
+  "stylesUseAltSyntax.module.scss.js",
 ]
 `;
 
-exports[`SASS CJS Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
+exports[`SASS CJS Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -185,19 +171,19 @@ exports[`SASS CJS Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS CJS Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.scss.js 1`] = `
-"module.exports = require(\\"./stylesUseAltSyntax.css\\");
+exports[`SASS CJS Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.scss.js 1`] = `
+"module.exports = require(\\"./stylesUseAltSyntax.module.css\\");
 module.exports.default = module.exports;"
 `;
 
-exports[`SASS CJS Shims stylesUseSyntax.sass: files 1`] = `
+exports[`SASS CJS Shims stylesUseSyntax.module.sass: files 1`] = `
 Array [
-  "stylesUseSyntax.css",
-  "stylesUseSyntax.sass.js",
+  "stylesUseSyntax.module.css",
+  "stylesUseSyntax.module.sass.js",
 ]
 `;
 
-exports[`SASS CJS Shims stylesUseSyntax.sass: stylesUseSyntax.css 1`] = `
+exports[`SASS CJS Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -251,7 +237,7 @@ exports[`SASS CJS Shims stylesUseSyntax.sass: stylesUseSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS CJS Shims stylesUseSyntax.sass: stylesUseSyntax.sass.js 1`] = `
-"module.exports = require(\\"./stylesUseSyntax.css\\");
+exports[`SASS CJS Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.sass.js 1`] = `
+"module.exports = require(\\"./stylesUseSyntax.module.css\\");
 module.exports.default = module.exports;"
 `;
diff --git a/build-tests/heft-sass-test/src/test/__snapshots__/lib-css.test.ts.snap b/build-tests/heft-sass-test/src/test/__snapshots__/lib-css.test.ts.snap
index 732c90b7f46..439187a2df7 100644
--- a/build-tests/heft-sass-test/src/test/__snapshots__/lib-css.test.ts.snap
+++ b/build-tests/heft-sass-test/src/test/__snapshots__/lib-css.test.ts.snap
@@ -4,13 +4,13 @@ exports[`SASS No Shims ignored1.scss: files 1`] = `Array []`;
 
 exports[`SASS No Shims ignored2.scss: files 1`] = `Array []`;
 
-exports[`SASS No Shims styles.sass: files 1`] = `
+exports[`SASS No Shims styles.module.sass: files 1`] = `
 Array [
-  "styles.css",
+  "styles.module.css",
 ]
 `;
 
-exports[`SASS No Shims styles.sass: styles.css 1`] = `
+exports[`SASS No Shims styles.module.sass: styles.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -95,14 +95,13 @@ exports[`SASS No Shims stylesAltSyntax.global.scss: stylesAltSyntax.global.css 1
 }"
 `;
 
-exports[`SASS No Shims stylesAltSyntax.scss: files 1`] = `
+exports[`SASS No Shims stylesAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesAltSyntax.css",
-  "stylesAltSyntax.global.css",
+  "stylesAltSyntax.module.css",
 ]
 `;
 
-exports[`SASS No Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
+exports[`SASS No Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -112,23 +111,13 @@ exports[`SASS No Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS No Shims stylesAltSyntax.scss: stylesAltSyntax.global.css 1`] = `
-"/**
- * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
- * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
- */
-.ms-label {
-  margin-bottom: 20px;
-}"
-`;
-
-exports[`SASS No Shims stylesUseAltSyntax.scss: files 1`] = `
+exports[`SASS No Shims stylesUseAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesUseAltSyntax.css",
+  "stylesUseAltSyntax.module.css",
 ]
 `;
 
-exports[`SASS No Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
+exports[`SASS No Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -166,13 +155,13 @@ exports[`SASS No Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS No Shims stylesUseSyntax.sass: files 1`] = `
+exports[`SASS No Shims stylesUseSyntax.module.sass: files 1`] = `
 Array [
-  "stylesUseSyntax.css",
+  "stylesUseSyntax.module.css",
 ]
 `;
 
-exports[`SASS No Shims stylesUseSyntax.sass: stylesUseSyntax.css 1`] = `
+exports[`SASS No Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
diff --git a/build-tests/heft-sass-test/src/test/__snapshots__/lib.test.ts.snap b/build-tests/heft-sass-test/src/test/__snapshots__/lib.test.ts.snap
index 078979eed43..3a5d74f9644 100644
--- a/build-tests/heft-sass-test/src/test/__snapshots__/lib.test.ts.snap
+++ b/build-tests/heft-sass-test/src/test/__snapshots__/lib.test.ts.snap
@@ -4,15 +4,15 @@ exports[`SASS ESM Shims ignored1.scss: files 1`] = `Array []`;
 
 exports[`SASS ESM Shims ignored2.scss: files 1`] = `Array []`;
 
-exports[`SASS ESM Shims styles.sass: files 1`] = `
+exports[`SASS ESM Shims styles.module.sass: files 1`] = `
 Array [
-  "styles.css",
-  "styles.sass.d.ts",
-  "styles.sass.js",
+  "styles.module.css",
+  "styles.module.sass.d.ts",
+  "styles.module.sass.js",
 ]
 `;
 
-exports[`SASS ESM Shims styles.sass: styles.css 1`] = `
+exports[`SASS ESM Shims styles.module.sass: styles.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -81,7 +81,7 @@ html, body {
 }"
 `;
 
-exports[`SASS ESM Shims styles.sass: styles.sass.d.ts 1`] = `
+exports[`SASS ESM Shims styles.module.sass: styles.module.sass.d.ts 1`] = `
 "declare interface IStyles {
   exampleImport: string;
   exampleApp: string;
@@ -91,7 +91,7 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS ESM Shims styles.sass: styles.sass.js 1`] = `"export { default } from \\"./styles.css\\";"`;
+exports[`SASS ESM Shims styles.module.sass: styles.module.sass.js 1`] = `"export { default } from \\"./styles.module.css\\";"`;
 
 exports[`SASS ESM Shims stylesAltSyntax.global.scss: files 1`] = `
 Array [
@@ -115,18 +115,15 @@ exports[`SASS ESM Shims stylesAltSyntax.global.scss: stylesAltSyntax.global.scss
 
 exports[`SASS ESM Shims stylesAltSyntax.global.scss: stylesAltSyntax.global.scss.js 1`] = `"import \\"./stylesAltSyntax.global.css\\";export {};"`;
 
-exports[`SASS ESM Shims stylesAltSyntax.scss: files 1`] = `
+exports[`SASS ESM Shims stylesAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesAltSyntax.css",
-  "stylesAltSyntax.global.css",
-  "stylesAltSyntax.global.scss.d.ts",
-  "stylesAltSyntax.global.scss.js",
-  "stylesAltSyntax.scss.d.ts",
-  "stylesAltSyntax.scss.js",
+  "stylesAltSyntax.module.css",
+  "stylesAltSyntax.module.scss.d.ts",
+  "stylesAltSyntax.module.scss.js",
 ]
 `;
 
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
+exports[`SASS ESM Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -136,21 +133,7 @@ exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.global.css 1`] = `
-"/**
- * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
- * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
- */
-.ms-label {
-  margin-bottom: 20px;
-}"
-`;
-
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.global.scss.d.ts 1`] = `"export {};"`;
-
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.global.scss.js 1`] = `"import \\"./stylesAltSyntax.global.css\\";export {};"`;
-
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.scss.d.ts 1`] = `
+exports[`SASS ESM Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.scss.d.ts 1`] = `
 "declare interface IStyles {
   label: string;
 }
@@ -158,17 +141,17 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS ESM Shims stylesAltSyntax.scss: stylesAltSyntax.scss.js 1`] = `"export { default } from \\"./stylesAltSyntax.css\\";"`;
+exports[`SASS ESM Shims stylesAltSyntax.module.scss: stylesAltSyntax.module.scss.js 1`] = `"export { default } from \\"./stylesAltSyntax.module.css\\";"`;
 
-exports[`SASS ESM Shims stylesUseAltSyntax.scss: files 1`] = `
+exports[`SASS ESM Shims stylesUseAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesUseAltSyntax.css",
-  "stylesUseAltSyntax.scss.d.ts",
-  "stylesUseAltSyntax.scss.js",
+  "stylesUseAltSyntax.module.css",
+  "stylesUseAltSyntax.module.scss.d.ts",
+  "stylesUseAltSyntax.module.scss.js",
 ]
 `;
 
-exports[`SASS ESM Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
+exports[`SASS ESM Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.css 1`] = `
 "/**
  * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -206,7 +189,7 @@ exports[`SASS ESM Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS ESM Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.scss.d.ts 1`] = `
+exports[`SASS ESM Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.scss.d.ts 1`] = `
 "declare interface IStyles {
   label: string;
   exampleList: string;
@@ -218,17 +201,17 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS ESM Shims stylesUseAltSyntax.scss: stylesUseAltSyntax.scss.js 1`] = `"export { default } from \\"./stylesUseAltSyntax.css\\";"`;
+exports[`SASS ESM Shims stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.scss.js 1`] = `"export { default } from \\"./stylesUseAltSyntax.module.css\\";"`;
 
-exports[`SASS ESM Shims stylesUseSyntax.sass: files 1`] = `
+exports[`SASS ESM Shims stylesUseSyntax.module.sass: files 1`] = `
 Array [
-  "stylesUseSyntax.css",
-  "stylesUseSyntax.sass.d.ts",
-  "stylesUseSyntax.sass.js",
+  "stylesUseSyntax.module.css",
+  "stylesUseSyntax.module.sass.d.ts",
+  "stylesUseSyntax.module.sass.js",
 ]
 `;
 
-exports[`SASS ESM Shims stylesUseSyntax.sass: stylesUseSyntax.css 1`] = `
+exports[`SASS ESM Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.css 1`] = `
 "/**
  * * This file gets transpiled by the heft-sass-plugin and output to the lib/ folder.
  * * Then Webpack uses css-loader to embed, and finally style-loader to apply it to the DOM.
@@ -282,7 +265,7 @@ exports[`SASS ESM Shims stylesUseSyntax.sass: stylesUseSyntax.css 1`] = `
 }"
 `;
 
-exports[`SASS ESM Shims stylesUseSyntax.sass: stylesUseSyntax.sass.d.ts 1`] = `
+exports[`SASS ESM Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.sass.d.ts 1`] = `
 "declare interface IStyles {
   exampleAnchor: string;
 }
@@ -290,4 +273,4 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS ESM Shims stylesUseSyntax.sass: stylesUseSyntax.sass.js 1`] = `"export { default } from \\"./stylesUseSyntax.css\\";"`;
+exports[`SASS ESM Shims stylesUseSyntax.module.sass: stylesUseSyntax.module.sass.js 1`] = `"export { default } from \\"./stylesUseSyntax.module.css\\";"`;
diff --git a/build-tests/heft-sass-test/src/test/__snapshots__/sass-ts.test.ts.snap b/build-tests/heft-sass-test/src/test/__snapshots__/sass-ts.test.ts.snap
index 7879c34de58..1c7500668ba 100644
--- a/build-tests/heft-sass-test/src/test/__snapshots__/sass-ts.test.ts.snap
+++ b/build-tests/heft-sass-test/src/test/__snapshots__/sass-ts.test.ts.snap
@@ -4,13 +4,13 @@ exports[`SASS Typings ignored1.scss: files 1`] = `Array []`;
 
 exports[`SASS Typings ignored2.scss: files 1`] = `Array []`;
 
-exports[`SASS Typings styles.sass: files 1`] = `
+exports[`SASS Typings styles.module.sass: files 1`] = `
 Array [
-  "styles.sass.d.ts",
+  "styles.module.sass.d.ts",
 ]
 `;
 
-exports[`SASS Typings styles.sass: styles.sass.d.ts 1`] = `
+exports[`SASS Typings styles.module.sass: styles.module.sass.d.ts 1`] = `
 "declare interface IStyles {
   exampleImport: string;
   exampleApp: string;
@@ -28,16 +28,13 @@ Array [
 
 exports[`SASS Typings stylesAltSyntax.global.scss: stylesAltSyntax.global.scss.d.ts 1`] = `"export {};"`;
 
-exports[`SASS Typings stylesAltSyntax.scss: files 1`] = `
+exports[`SASS Typings stylesAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesAltSyntax.global.scss.d.ts",
-  "stylesAltSyntax.scss.d.ts",
+  "stylesAltSyntax.module.scss.d.ts",
 ]
 `;
 
-exports[`SASS Typings stylesAltSyntax.scss: stylesAltSyntax.global.scss.d.ts 1`] = `"export {};"`;
-
-exports[`SASS Typings stylesAltSyntax.scss: stylesAltSyntax.scss.d.ts 1`] = `
+exports[`SASS Typings stylesAltSyntax.module.scss: stylesAltSyntax.module.scss.d.ts 1`] = `
 "declare interface IStyles {
   label: string;
 }
@@ -45,13 +42,13 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS Typings stylesUseAltSyntax.scss: files 1`] = `
+exports[`SASS Typings stylesUseAltSyntax.module.scss: files 1`] = `
 Array [
-  "stylesUseAltSyntax.scss.d.ts",
+  "stylesUseAltSyntax.module.scss.d.ts",
 ]
 `;
 
-exports[`SASS Typings stylesUseAltSyntax.scss: stylesUseAltSyntax.scss.d.ts 1`] = `
+exports[`SASS Typings stylesUseAltSyntax.module.scss: stylesUseAltSyntax.module.scss.d.ts 1`] = `
 "declare interface IStyles {
   label: string;
   exampleList: string;
@@ -63,13 +60,13 @@ declare const styles: IStyles;
 export default styles;"
 `;
 
-exports[`SASS Typings stylesUseSyntax.sass: files 1`] = `
+exports[`SASS Typings stylesUseSyntax.module.sass: files 1`] = `
 Array [
-  "stylesUseSyntax.sass.d.ts",
+  "stylesUseSyntax.module.sass.d.ts",
 ]
 `;
 
-exports[`SASS Typings stylesUseSyntax.sass: stylesUseSyntax.sass.d.ts 1`] = `
+exports[`SASS Typings stylesUseSyntax.module.sass: stylesUseSyntax.module.sass.d.ts 1`] = `
 "declare interface IStyles {
   exampleAnchor: string;
 }
diff --git a/build-tests/heft-sass-test/src/utilities/configurableModule.sass b/build-tests/heft-sass-test/src/utilities/_configurableModule.sass
similarity index 100%
rename from build-tests/heft-sass-test/src/utilities/configurableModule.sass
rename to build-tests/heft-sass-test/src/utilities/_configurableModule.sass
diff --git a/build-tests/heft-sass-test/src/utilities/relativeImport.sass b/build-tests/heft-sass-test/src/utilities/_relativeImport.sass
similarity index 98%
rename from build-tests/heft-sass-test/src/utilities/relativeImport.sass
rename to build-tests/heft-sass-test/src/utilities/_relativeImport.sass
index 49289ad2a51..627b27fa18e 100644
--- a/build-tests/heft-sass-test/src/utilities/relativeImport.sass
+++ b/build-tests/heft-sass-test/src/utilities/_relativeImport.sass
@@ -1,5 +1,5 @@
-/**
- * This file is not used by the example component. However, it verifies that relative Sass imports are successful.
+/**
+ * This file is not used by the example component. However, it verifies that relative Sass imports are successful.
  */
 
 @import '../stylesImport'
\ No newline at end of file
diff --git a/build-tests/heft-sass-test/src/utilities/useSyntaxRelativeImport.sass b/build-tests/heft-sass-test/src/utilities/_useSyntaxRelativeImport.sass
similarity index 100%
rename from build-tests/heft-sass-test/src/utilities/useSyntaxRelativeImport.sass
rename to build-tests/heft-sass-test/src/utilities/_useSyntaxRelativeImport.sass
diff --git a/common/changes/@rushstack/heft-sass-plugin/sass-partials_2025-05-12-22-27.json b/common/changes/@rushstack/heft-sass-plugin/sass-partials_2025-05-12-22-27.json
new file mode 100644
index 00000000000..ef02fe4ebd5
--- /dev/null
+++ b/common/changes/@rushstack/heft-sass-plugin/sass-partials_2025-05-12-22-27.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-sass-plugin",
+      "comment": "Fix an issue where the SCSS module classifier evaluated SCSS partials instead of ignoring them (since they aren't directly importable).",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/heft-sass-plugin"
+}
\ No newline at end of file
diff --git a/heft-plugins/heft-sass-plugin/src/SassProcessor.ts b/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
index 3c8719653c8..76b4db9d83e 100644
--- a/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
+++ b/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
@@ -607,7 +607,8 @@ export class SassProcessor {
       const url: URL = pathToHeftUrl(absolutePath);
 
       const isPartial: boolean = isSassPartial(absolutePath);
-      const isModule: boolean = this._isFileModule(absolutePath);
+      // SCSS partials are not modules, insofar as they cannot be imported directly.
+      const isModule: boolean = isPartial ? false : this._isFileModule(absolutePath);
 
       const fileRecord: IFileRecord = {
         absolutePath,
@@ -670,7 +671,7 @@ export class SassProcessor {
     let record: IFileRecord | undefined = this._fileInfo.get(filePath);
     if (!record) {
       const isPartial: boolean = isSassPartial(filePath);
-      const isModule: boolean = this._isFileModule(filePath);
+      const isModule: boolean = isPartial ? false : this._isFileModule(filePath);
       const url: URL = pathToHeftUrl(filePath);
       record = {
         absolutePath: filePath,