# How To Change the Application Theme

The application theme is set using the `themeName` prop in ApplicationBase. The `themeName` is used as the class name for applying styles.

A `terra-theme.config.js` file must be available to enable themes. Check out the [theme strategy guide](/guides/terra-application/theme-strategy) for more information about using and applying themes.

```jsx
  import React from 'react';
  import ApplicationBase from 'terra-application/lib/application-base';

  const ExampleApp = () => (
    <ApplicationBase themeName="example-theme-name">
      {...}
    </ApplicationBase>
  );

  export default ExampleApp;
```