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. (PsycINFO Database Record (c) 2018 APA, all rights reserved).