As a psychologist working with individuals, couples, and groups over the past 25 years, I have become convinced that group therapy holds effective possibilities for treatment that neither individual nor couples therapy can match. In theorizing about why group work holds such potency for changing lives, I have come to place it in a Sartrean context. I believe that group therapy offers a greater possibility for revolutionary praxis than individual or couples therapy. In saying this, I am not talking about political or social revolution, but rather the possibility for radical change in a person's orientation toward the world, which groups tend to provoke and reinforce in a way that is more difficult in other forms of therapy. Sartre's concept of groups in his later philosophy, especially in Search for a Method and the Critique of Dialectical Reason, can help us to understand better this transformative power of groups. Such power is not always positive, of course, as Sartre himself recognizes—and as social and political history so amply demonstrates. But the nature of therapy groups is such that they at least have the potential for positive results.