Congruence or genuineness is a relationship element with an extensive and important history within psychotherapy. Congruence is an aspect of the therapy relationship with two facets, one intrapersonal and one interpersonal. Mindful genuineness, personal awareness, and authenticity characterize the intrapersonal element. The capacity to respectfully and transparently give voice to ones’ experience to another person characterizes the interpersonal component. Although most fully developed in the person-centered tradition, congruence is highly valued in many theoretical orientations. In this article, we define and provide clinical examples of congruence. We also present an original meta-analysis of its relation with psychotherapy improvement. An analysis of 21 studies (k), representing 1,192 patients (N), resulted in a weighted aggregate effect size (r) of .23 (95% confidence interval = [.13, .32]) or an estimated d of .46. Moderators of the association between congruence and outcome are also investigated. In closing, we address patient contributions, limitations of the extant research, diversity considerations, and therapeutic practices that might promote congruence and improve psychotherapy outcomes.