diff --git a/test/Templates.Test/Helpers/Node/install-via-yarn-with-shrinkwrap.js b/test/Templates.Test/Helpers/Node/install-via-yarn-with-shrinkwrap.js
deleted file mode 100644
index 280d7e2d96..0000000000
--- a/test/Templates.Test/Helpers/Node/install-via-yarn-with-shrinkwrap.js
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
-==============================================================================================
-Implementation based on https://github.com/dabroek/shrinkwrap-to-lockfile/ by Matthijs Dabroek
-
-License for original package:
-MIT License
-
-Copyright (c) 2017 Matthijs Dabroek
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-==============================================================================================
-
-Modified to support execution across multiple directories simultaneously,
-to provide console output while executing, and to eliminate lodash dependency.
-*/
-
-const fs = require('fs');
-const path = require('path');
-const execSync = require('child_process').execSync;
-
-function parseJsonFile(filename) {
-  let obj = {};
-
-  try {
-    const file = fs.readFileSync(path.resolve(process.cwd(), filename), 'utf8');
-    obj = JSON.parse(file);
-  } catch (error) {
-    throw new Error(`${filename} could not be parsed.`);
-  }
-
-  return obj;
-}
-
-function getDependencyVersions(dependencies) {
-  const result = {};
-  for (const name in dependencies) {
-    if (dependencies.hasOwnProperty(name)) {
-      const pkg = dependencies[name];
-      const version = pkg.version || pkg;
-      result[name] = version.match(/(\d+\.\d+\.\d+(?:-.+)?)/)[0];
-    }
-  }
-  return result;
-}
-
-function objectMergeLeft(a, b) {
-  return _.reduce(a, (result, value, key) => {
-    result[key] = value;
-
-    if (!_.isEqual(value, b[key])) {
-      result[key] = b[key];
-    }
-
-    return result;
-  }, {});
-}
-
-function updatePackageJson(shrinkwrapFile, packageFile) {
-  const packageFilePath = path.resolve(process.cwd(), packageFile);
-  const origPackageFileContents = fs.readFileSync(packageFilePath);
-  const shrinkwrapJson = parseJsonFile(shrinkwrapFile);
-  const packageJson = parseJsonFile(packageFile);
-
-  packageJson.dependencies = getDependencyVersions(shrinkwrapJson.dependencies);
-  delete packageJson.devDependencies;
-
-  fs.writeFileSync(packageFilePath, JSON.stringify(packageJson, null, 2));
-  return {
-    dispose: () => {
-      fs.writeFileSync(packageFilePath, origPackageFileContents);
-    }
-  };
-}
-
-const temporaryPackageJson = updatePackageJson('npm-shrinkwrap.json', 'package.json');
-try {
-  console.log('Generating yarn.lock from npm-shrinkwrap.json...');
-  execSync('yarn install --mutex network', { stdio: 'inherit' });
-} finally {
-  temporaryPackageJson.dispose();
-}
diff --git a/test/Templates.Test/Helpers/TemplateTestBase.cs b/test/Templates.Test/Helpers/TemplateTestBase.cs
index 68c7a6cdc2..f85470db4a 100644
--- a/test/Templates.Test/Helpers/TemplateTestBase.cs
+++ b/test/Templates.Test/Helpers/TemplateTestBase.cs
@@ -16,6 +16,7 @@ namespace Templates.Test
     public class TemplateTestBase : IDisposable
     {
         private static object DotNetNewLock = new object();
+        private static object NpmInstallLock = new object();
 
         protected string ProjectName { get; set; }
         protected string TemplateOutputDir { get; private set; }
@@ -75,27 +76,14 @@ namespace Templates.Test
 
         protected void InstallNpmPackages(string relativePath)
         {
-            var fullPath = Path.Combine(TemplateOutputDir, relativePath);
-
-            if (!HasYarnInstalled())
+            // It's not safe to run multiple NPM installs in parallel
+            // https://github.com/npm/npm/issues/2500
+            lock (NpmInstallLock)
             {
-                Output.WriteLine($"Restoring NPM packages in '{relativePath}' using npm because yarn is not installed...");
+                var fullPath = Path.Combine(TemplateOutputDir, relativePath);
+                Output.WriteLine($"Restoring NPM packages in '{relativePath}' using npm...");
                 RunViaShell(fullPath, "npm install");
             }
-            else
-            {
-                // Current versions of NPM produce random errors when run on Windows
-                // (e.g., https://github.com/npm/npm/issues/19004). Plus, it's very slow to
-                // restore the SPA template packages. To make CI faster and more reliable, use
-                // Yarn to install the packages. To make Yarn respect the npm-shrinkwrap.json
-                // files, run a script that temporarily replaces the package.json content using
-                // dependency information from npm-shrinkwrap.json.
-                var installViaYarnWithShrinkwrapScriptPath = Path.Combine(
-                    Path.GetDirectoryName(typeof(TemplateTestBase).Assembly.Location),
-                    @"..\..\..\Helpers\Node\install-via-yarn-with-shrinkwrap.js");
-                Output.WriteLine($"Restoring NPM packages in '{relativePath}' using yarn...");
-                RunViaShell(fullPath, $"node {installViaYarnWithShrinkwrapScriptPath}");
-            }
         }
 
         private void RunViaShell(string workingDirectory, string commandAndArgs)
@@ -108,19 +96,6 @@ namespace Templates.Test
                 .WaitForExit(assertSuccess: true);
         }
 
-        private bool HasYarnInstalled()
-        {
-            try
-            {
-                RunViaShell(TemplateOutputDir, "yarn --version");
-                return true;
-            }
-            catch
-            {
-                return false;
-            }
-        }
-
         protected void AssertDirectoryExists(string path, bool shouldExist)
         {
             var fullPath = Path.Combine(TemplateOutputDir, path);