Perhaps the most complex and controversial role for the computer in clinical practice is as a treatment medium in which the computer effectively replaces the psychotherapist. This article outlines the historical development of computer treatment, from dialogue generators in the 1960s through to the interactive, multimedia programs of the 2000s. In evaluating the most recent developments in computer treatment, we present a small meta-analytic study demonstrating large effect sizes in favor of computer treatments for anxiety and depression for pre/post outcomes and treatment as usual/waitlist comparators. Next, we review studies of the cost effectiveness of computer treatments. Finally, we outline the implications for research, policy, and practice of this new generation of treatment options.