diff --git a/packages/core/__tests__/config/load-config.test.ts b/packages/core/__tests__/config/load-config.test.ts
index d147c88e5..ea4ac1af5 100644
--- a/packages/core/__tests__/config/load-config.test.ts
+++ b/packages/core/__tests__/config/load-config.test.ts
@@ -3,7 +3,7 @@ import * as os from 'node:os';
 import { describe, beforeEach, afterEach, test, expect, vi } from 'vitest';
 import { loadConfig } from '../../src/config/index.js';
 import { normalizePath } from '../../src/config/config.js';
-import { require } from '../../src/config/loader.js';
+import { findTypeScript, loadConfigInput, require } from '../../src/config/loader.js';
 
 describe('Config: loadConfig', () => {
   const testDir = `${os.tmpdir()}/glint-config-test-load-config-${process.pid}`;
@@ -51,6 +51,87 @@ describe('Config: loadConfig', () => {
     expect(config.environment.getConfiguredTemplateTags()).toEqual({ test: {} });
   });
 
+  test('recursively extends config', () => {
+    fs.mkdirSync(`${testDir}/deeply/nested/directory`, { recursive: true });
+    fs.mkdirSync(`${testDir}/other`, { recursive: true });
+
+    fs.writeFileSync(
+      `${testDir}/tsconfig.json`,
+      JSON.stringify({
+        extends: './other/tsconfig.json',
+        glint: {
+          environment: '../local-env',
+        },
+      }),
+    );
+    fs.writeFileSync(
+      `${testDir}/other/tsconfig.json`,
+      JSON.stringify({
+        glint: {
+          environment: 'kaboom',
+        },
+      }),
+    );
+
+    fs.writeFileSync(
+      `${testDir}/deeply/tsconfig.json`,
+      JSON.stringify({
+        extends: '../tsconfig.json',
+      }),
+    );
+
+    let ts = findTypeScript(`${testDir}/deeply`);
+    if (!ts) {
+      expect.fail('TypeScript not found');
+    }
+    let glintConfig = loadConfigInput(ts, `${testDir}/deeply/tsconfig.json`);
+    expect(glintConfig).toEqual({ environment: '../local-env' });
+
+    let config = loadConfig(`${testDir}/deeply/nested/directory`);
+    expect(config.rootDir).toBe(normalizePath(`${testDir}/deeply`));
+  });
+
+  test('extends multiple parents', () => {
+    fs.mkdirSync(`${testDir}/deeply/nested/directory`, { recursive: true });
+    fs.mkdirSync(`${testDir}/other`, { recursive: true });
+
+    fs.writeFileSync(
+      `${testDir}/tsconfig.json`,
+      JSON.stringify({
+        glint: {
+          environment: 'kaboom',
+          checkStandaloneTemplates: true,
+        },
+      }),
+    );
+    fs.writeFileSync(
+      `${testDir}/other/tsconfig.json`,
+      JSON.stringify({
+        glint: {
+          environment: '../local-env',
+        },
+      }),
+    );
+
+    fs.writeFileSync(
+      `${testDir}/deeply/tsconfig.json`,
+      JSON.stringify({
+        extends: ['../tsconfig.json', '../other/tsconfig.json'],
+      }),
+    );
+
+    let ts = findTypeScript(`${testDir}/deeply`);
+    if (!ts) {
+      expect.fail('TypeScript not found');
+    }
+    let glintConfig = loadConfigInput(ts, `${testDir}/deeply/tsconfig.json`);
+    expect(glintConfig).toEqual({ environment: '../local-env', checkStandaloneTemplates: true });
+
+    let config = loadConfig(`${testDir}/deeply/nested/directory`);
+    expect(config.rootDir).toBe(normalizePath(`${testDir}/deeply`));
+    expect(config.environment.names).toEqual(['../local-env']);
+  });
+
   test('locates config in package', () => {
     const directory = `${testDir}/package-glint-config`;
     const nodeModulePackageDir = `${directory}/node_modules/@package1`;
diff --git a/packages/core/src/config/loader.ts b/packages/core/src/config/loader.ts
index cc32d6804..798dcdcd8 100644
--- a/packages/core/src/config/loader.ts
+++ b/packages/core/src/config/loader.ts
@@ -67,36 +67,43 @@ function tryResolve<T>(load: () => T): T | null {
   }
 }
 
-function loadConfigInput(ts: TypeScript, entryPath: string): GlintConfigInput | null {
-  let fullGlintConfig: Record<string, unknown> = {};
-  let currentPath: string | undefined = entryPath;
+function parseConfigInput(
+  ts: TypeScript,
+  entryPath: string,
+  currentPath: string,
+  fullGlintConfig: Record<string, unknown>,
+): Record<string, unknown> {
+  let currentContents: any = ts.readConfigFile(currentPath, ts.sys.readFile).config;
+  let currentGlintConfig = currentContents.glint ?? {};
 
-  while (currentPath) {
-    let currentContents: any = ts.readConfigFile(currentPath, ts.sys.readFile).config;
-    let currentGlintConfig = currentContents.glint ?? {};
-
-    assert(
-      currentPath === entryPath || !currentGlintConfig.transform,
-      'Glint `transform` options may not be specified in extended config.',
-    );
-
-    fullGlintConfig = { ...currentGlintConfig, ...fullGlintConfig };
+  assert(
+    currentPath === entryPath || !currentGlintConfig.transform,
+    'Glint `transform` options may not be specified in extended config.',
+  );
 
-    if (currentContents.extends) {
-      currentPath = path.resolve(path.dirname(currentPath), currentContents.extends);
-      if (!fs.existsSync(currentPath)) {
+  if (currentContents.extends) {
+    let paths: string[] = Array.isArray(currentContents.extends)
+      ? currentContents.extends
+      : [currentContents.extends];
+    for (let extendPath of paths) {
+      let currentExtendPath = path.resolve(path.dirname(currentPath), extendPath);
+      if (!fs.existsSync(currentExtendPath)) {
         try {
-          currentPath = require.resolve(currentContents.extends);
+          currentExtendPath = require.resolve(currentContents.extends);
         } catch {
           // suppress the exception thrown by require.resolve for those scenarios where the file does not exist
         }
       }
-    } else {
-      currentPath = undefined;
+
+      fullGlintConfig = parseConfigInput(ts, entryPath, currentExtendPath, fullGlintConfig);
     }
   }
 
-  return validateConfigInput(fullGlintConfig);
+  return { ...fullGlintConfig, ...currentGlintConfig };
+}
+
+export function loadConfigInput(ts: TypeScript, entryPath: string): GlintConfigInput | null {
+  return validateConfigInput(parseConfigInput(ts, entryPath, entryPath, {}));
 }
 
 function findNearestConfigFile(ts: TypeScript, searchFrom: string): string {