In this article, we review the history and definition of countertransference as well as empirical research on countertransference, its management, and the relation of both to psychotherapy outcome. Three meta-analyses are presented, as well as studies that illustrate findings from the meta-analyses. The first meta-analysis indicated that countertransference reactions are related inversely and modestly to psychotherapy outcomes (overall weighted effect r = -.16, p = .002, 95% CI [-.26, -.06], k = 10 studies, N = 769 participants). The second meta-analysis suggested that countertransference management factors that have been studied to date play little to no role in actually attenuating countertransference reactions (r = -.14, p = .10, 95% CI [-.30, .03], k = 11 studies, N = 1065 participants). However, the final meta-analysis revealed that managing countertransference successfully is related to better therapy outcomes (r = .56, p = .000, 95% CI [.40, .73], k = 7 studies, N = 478 participants). We conclude by summarizing the limitations of the research base and highlighting the therapeutic practices predicated on research.