Radio has been 'repositioned' by TV as a 'less' effective medium for brand building. Media research often addresses the question 'How does radio as a medium differ from other channels?' instead of the more important question 'What can radio do for brand building?' This paper challenges the idea that radio is a tertiary medium of little use in brand building. Recent research from around the world is reviewed to show how radio advertising can be used to build brands and stimulate sales. As the return on investment in TV advertising declines, this paper invites marketers to become more radio active.