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 with 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 (r = −.16, p = .02, 95% CI [−.30, −.03], d = −0.33, k = 14 studies, N = 973). A second meta-analysis supported the notion that countertransference management factors attenuate countertransference reactions (r = −.27, p = .001, 95% CI [−.43, −.10], d = −0.55, k = 13 studies, N = 1,065). The final meta-analysis revealed that successful countertransference management is related to better therapy outcomes (r = .39, p < .001, 95% CI [.17, .60], d = 0.84, k = 9 studies, N = 392 participants). In all meta-analyses, there was significant heterogeneity across studies. We conclude by summarizing the limitations of the research base and highlighting the therapeutic practices predicated on research.