diff --git a/src/__tests__/ui/box/container.test.jsx b/src/__tests__/ui/box/container.test.jsx
index e248a1875..2695650e9 100644
--- a/src/__tests__/ui/box/container.test.jsx
+++ b/src/__tests__/ui/box/container.test.jsx
@@ -9,6 +9,10 @@ jest.mock('store/index', () => ({
 
 jest.mock('ui/box/chrome', () => mockComponent('chrome'));
 
+jest.mock('connection/database/index', () => ({
+  databaseUsernameValue: jest.fn()
+}));
+
 const mockEvent = {
   preventDefault: () => {}
 };
@@ -75,14 +79,25 @@ describe('Container', () => {
   describe('with a custom `connectionResolver`', () => {
     let connectionResolverMock;
     let setResolvedConnectionMock;
+    let databaseUsernameValueMock;
 
     beforeEach(() => {
       connectionResolverMock = jest.fn();
       setResolvedConnectionMock = jest.fn();
+      databaseUsernameValueMock = require('connection/database/index').databaseUsernameValue;
+
+      // Set default return value for databaseUsernameValue mock
+      databaseUsernameValueMock.mockReturnValue('peter_picked@pickledpepper.com');
+
       require('core/index').connectionResolver = () => connectionResolverMock;
       require('core/index').setResolvedConnection = setResolvedConnectionMock;
     });
 
+    afterEach(() => {
+      // Reset mock between tests and restore default return value
+      databaseUsernameValueMock.mockReset().mockReturnValue('peter_picked@pickledpepper.com');
+    });
+
     it('calls `connectionResolver` onSubmit', () => {
       const c = getContainer();
       c.handleSubmit(mockEvent);
@@ -110,6 +125,54 @@ describe('Container', () => {
       expect(mock.calls.length).toBe(1);
       expect(mock.calls[0]).toMatchSnapshot();
     });
+
+    it('prioritizes email over username on signUp screen', () => {
+      databaseUsernameValueMock.mockReturnValue('test@example.com');
+
+      const c = getContainer({ screenName: 'main.signUp' });
+      c.handleSubmit(mockEvent);
+
+      // Should call databaseUsernameValue with emailFirst: true
+      expect(databaseUsernameValueMock).toHaveBeenCalledWith(
+        expect.anything(),
+        { emailFirst: true }
+      );
+
+      // connectionResolver should receive the email value
+      const { mock } = connectionResolverMock;
+      expect(mock.calls[0][0]).toBe('test@example.com');
+    });
+
+    it('prioritizes username over email on login screen', () => {
+      databaseUsernameValueMock.mockReturnValue('testuser');
+
+      const c = getContainer({ screenName: 'main.login' });
+      c.handleSubmit(mockEvent);
+
+      // Should call databaseUsernameValue with empty options (default behavior)
+      expect(databaseUsernameValueMock).toHaveBeenCalledWith(
+        expect.anything(),
+        {}
+      );
+
+      // connectionResolver should receive the username value
+      const { mock } = connectionResolverMock;
+      expect(mock.calls[0][0]).toBe('testuser');
+    });
+
+    it('uses default behavior when screenName is not main.signUp', () => {
+      databaseUsernameValueMock.mockReturnValue('defaultvalue');
+
+      const c = getContainer({ screenName: 'forgotPassword' });
+      c.handleSubmit(mockEvent);
+
+      // Should call databaseUsernameValue with empty options (default behavior)
+      expect(databaseUsernameValueMock).toHaveBeenCalledWith(
+        expect.anything(),
+        {}
+      );
+    });
+
   });
 
   describe('when suppressSubmitOverlay is true', () => {
diff --git a/src/ui/box/container.jsx b/src/ui/box/container.jsx
index 66fbf0e51..5d8b8ba5e 100644
--- a/src/ui/box/container.jsx
+++ b/src/ui/box/container.jsx
@@ -5,6 +5,7 @@ import { CloseButton } from './button';
 import * as l from '../../core/index';
 import * as c from '../../field/index';
 import { swap, updateEntity } from '../../store/index';
+import { databaseUsernameValue } from '../../connection/database/index';
 
 const badgeSvg = (
   <svg focusable="false" width="58px" height="21px" viewBox="0 0 462 168">
@@ -69,7 +70,7 @@ export default class Container extends React.Component {
     this.state = { isOpen: false };
   }
   checkConnectionResolver(done) {
-    const { contentProps } = this.props;
+    const { contentProps, screenName } = this.props;
     const lock = contentProps.model;
     const connectionResolver = l.connectionResolver(lock);
     if (!connectionResolver) {
@@ -77,7 +78,12 @@ export default class Container extends React.Component {
     }
     const { connections, id } = lock.get('client').toJS();
     const context = { connections, id };
-    const userInputValue = c.getFieldValue(lock, 'username') || c.getFieldValue(lock, 'email');
+
+    // On signUp screen, use emailFirst option to prioritize email over username
+    // On login screen, use default behavior (username first)
+    const isSignUpScreen = screenName === 'main.signUp';
+    const userInputValue = databaseUsernameValue(lock, isSignUpScreen ? { emailFirst: true } : {});
+
     connectionResolver(userInputValue, context, resolvedConnection => {
       swap(updateEntity, 'lock', l.id(lock), m => l.setResolvedConnection(m, resolvedConnection));
       done();