In this chapter, I retrieve Philip Brickman’s commitment theory of mental health, which contains a unified theory of three emotions: jealousy, guilt, and depression. According to Brickman, commitment is a dialectical process of resolving ambivalence, which is necessary for mental health and subjective well-being (i.e., happiness). From this, it follows that any threat to or loss of commitment may result in adverse emotional reactions. In particular: (1) external threats to commitment result in jealousy; (2) internal threats to commitment result in guilt; and (3) loss of commitment results in depression. The chapter describes how these emotions may be unhelpful and destructive, but may also be harnessed to repair commitments or build new ones, thus promoting mental health. After outlining Brickman’s unified theory of emotions, I explore its relevance to clinical issues, including borderline personality disorder, moral injury, addictions, couples, intimate partner violence, polyamory, parenting, and grief and loss. The chapter concludes with a discussion of limitations and situates Brickman’s work in the history of positive psychology. Whereas Brickman’s commitment theory of mental health predates the emergence of what’s been called positive psychology 1.0, it anticipates many of the themes found in the so-called positive psychology 2.0 and 3.0, including viewing emotions dialectically and with increasing complexity.