diff --git a/common/reviews/api/rush-lib.api.md b/common/reviews/api/rush-lib.api.md
index da26a3aa3ec..37a1f05dbfa 100644
--- a/common/reviews/api/rush-lib.api.md
+++ b/common/reviews/api/rush-lib.api.md
@@ -798,6 +798,8 @@ export class RushConfigurationProject {
     get rushConfiguration(): RushConfiguration;
     get shouldPublish(): boolean;
     get skipRushCheck(): boolean;
+    // (undocumented)
+    readonly splitWorkspace: boolean;
     // @beta
     get tags(): ReadonlySet<string>;
     get tempProjectName(): string;
diff --git a/libraries/rush-lib/src/api/RushConfiguration.ts b/libraries/rush-lib/src/api/RushConfiguration.ts
index 9f9df7cf9fc..24498991721 100644
--- a/libraries/rush-lib/src/api/RushConfiguration.ts
+++ b/libraries/rush-lib/src/api/RushConfiguration.ts
@@ -4,6 +4,7 @@
 /* eslint max-lines: off */
 
 import * as path from 'path';
+import * as process from 'process';
 import * as semver from 'semver';
 import {
   JsonFile,
@@ -769,9 +770,14 @@ export class RushConfiguration {
     this._projects = [];
     this._projectsByName = new Map<string, RushConfigurationProject>();
 
+    let filteredProjects: IRushConfigurationProjectJson[] = this._rushConfigurationJson.projects;
+    if (process.argv.indexOf('install') >= 0 || process.argv.indexOf('update') >= 0) {
+      filteredProjects = filteredProjects.filter((x) => !x.splitWorkspace);
+    }
+
     // We sort the projects array in alphabetical order.  This ensures that the packages
     // are processed in a deterministic order by the various Rush algorithms.
-    const sortedProjectJsons: IRushConfigurationProjectJson[] = this._rushConfigurationJson.projects.slice(0);
+    const sortedProjectJsons: IRushConfigurationProjectJson[] = filteredProjects.slice(0);
     sortedProjectJsons.sort((a: IRushConfigurationProjectJson, b: IRushConfigurationProjectJson) =>
       a.packageName.localeCompare(b.packageName)
     );
diff --git a/libraries/rush-lib/src/api/RushConfigurationProject.ts b/libraries/rush-lib/src/api/RushConfigurationProject.ts
index 7fa43a5d801..fea5dacbee5 100644
--- a/libraries/rush-lib/src/api/RushConfigurationProject.ts
+++ b/libraries/rush-lib/src/api/RushConfigurationProject.ts
@@ -25,6 +25,7 @@ export interface IRushConfigurationProjectJson {
   skipRushCheck?: boolean;
   publishFolder?: string;
   tags?: string[];
+  splitWorkspace?: boolean;
 }
 
 /**
@@ -77,6 +78,8 @@ export class RushConfigurationProject {
   private _dependencyProjects: Set<RushConfigurationProject> | undefined = undefined;
   private _consumingProjects: Set<RushConfigurationProject> | undefined = undefined;
 
+  public readonly splitWorkspace: boolean;
+
   /** @internal */
   public constructor(options: IRushConfigurationProjectOptions) {
     const { projectJson, rushConfiguration, tempProjectName, allowedProjectTags } = options;
@@ -187,6 +190,8 @@ export class RushConfigurationProject {
     } else {
       this._tags = new Set(projectJson.tags);
     }
+
+    this.splitWorkspace = !!projectJson.splitWorkspace;
   }
 
   /**
diff --git a/libraries/rush-lib/src/schemas/rush.schema.json b/libraries/rush-lib/src/schemas/rush.schema.json
index 967031824ac..92d757d710b 100644
--- a/libraries/rush-lib/src/schemas/rush.schema.json
+++ b/libraries/rush-lib/src/schemas/rush.schema.json
@@ -294,7 +294,7 @@
             }
           }
         },
-        "additionalProperties": false,
+        "additionalProperties": true,
         "required": ["packageName", "projectFolder"]
       }
     },