diff --git a/src/global.ts b/src/global.ts
index 0f5815819..ba2e23f9c 100644
--- a/src/global.ts
+++ b/src/global.ts
@@ -83,7 +83,10 @@ export class Global {
    * ```
    */
   public static getEnvironmentMode(): Mode {
-    return Mode[env.getKeyOf('SFDX_ENV', Mode, Mode.PRODUCTION, (value) => value.toUpperCase())];
+    const envValue = env.getString('SF_ENV') ?? env.getString('SFDX_ENV', Mode.PRODUCTION);
+    return envValue in Mode || envValue.toUpperCase() in Mode
+      ? Mode[envValue.toUpperCase() as keyof typeof Mode]
+      : Mode.PRODUCTION;
   }
 
   /**
diff --git a/test/unit/globalTest.ts b/test/unit/globalTest.ts
index cae4620e4..828c1d906 100644
--- a/test/unit/globalTest.ts
+++ b/test/unit/globalTest.ts
@@ -9,10 +9,16 @@ import { Global, Mode } from '../../src/global';
 
 describe('Global', () => {
   describe('environmentMode', () => {
-    const sfdxEnv = process.env.SFDX_ENV;
+    const original = { SFDX_ENV: process.env.SFDX_ENV, SF_ENV: process.env.SF_ENV };
+
+    beforeEach(() => {
+      delete process.env.SFDX_ENV;
+      delete process.env.SF_ENV;
+    });
 
     after(() => {
-      process.env.SFDX_ENV = sfdxEnv;
+      process.env.SFDX_ENV = original.SFDX_ENV;
+      process.env.SF_ENV = original.SF_ENV;
     });
 
     it('uses SFDX_ENV mode', () => {
@@ -23,8 +29,48 @@ describe('Global', () => {
       expect(Global.getEnvironmentMode() === Mode.TEST).to.be.false;
     });
 
+    it('prefers SF_ENV mode', () => {
+      process.env.SF_ENV = 'test';
+      process.env.SFDX_ENV = 'development';
+      expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.TEST).to.be.true;
+    });
+
+    it('finds uppercase', () => {
+      process.env.SF_ENV = 'TEST';
+      expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.TEST).to.be.true;
+    });
+
+    it('finds lowercase', () => {
+      process.env.SF_ENV = 'demo';
+      expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.true;
+      expect(Global.getEnvironmentMode() === Mode.TEST).to.be.false;
+    });
+
+    it('finds mixed case', () => {
+      process.env.SF_ENV = 'dEvelOpment';
+      expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.true;
+      expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.TEST).to.be.false;
+    });
+
     it('is production by default', () => {
-      delete process.env.SFDX_ENV;
+      expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.true;
+      expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.false;
+      expect(Global.getEnvironmentMode() === Mode.TEST).to.be.false;
+    });
+
+    it('defaults to production when invalid values are specified', () => {
+      process.env.SFDX_ENV = 'notARealMode';
       expect(Global.getEnvironmentMode() === Mode.DEVELOPMENT).to.be.false;
       expect(Global.getEnvironmentMode() === Mode.PRODUCTION).to.be.true;
       expect(Global.getEnvironmentMode() === Mode.DEMO).to.be.false;