This article introduces the journal issue devoted to the most recent iteration of evidence-based psychotherapy relationships and frames it within the work of the Third Interdivisional American Psychological Association Task Force on Evidence-Based Relationships and Responsiveness. The authors summarize the overarching purposes and processes of the Task Force and trace the devaluation of the therapy relationship in contemporary treatment guidelines and evidence-based practices. The article outlines the meta-analytic results of the subsequent 16 articles in the issue, each devoted to the link between a particular relationship element and treatment outcome. The expert consensus deemed 9 of the relationship elements as demonstrably effective, 7 as probably effective, and 1 as promising but with insufficient research to judge. What works-and what does not-in the therapy relationship is emphasized throughout. The limitations of the task force work are also addressed. The article closes with the Task Force's formal conclusions and 28 recommendations. The authors conclude that decades of research evidence and clinical experience converge: The psychotherapy relationship makes substantial and consistent contributions to outcome independent of the type of treatment. Clinical Impact Statement Question: What, specifically, is effective in the powerful psychotherapy relationship? Findings: Clinicians can use these meta-analytic conclusions and the practice recommendations of the Task Force on Evidence-Based Relationships and Responsiveness to provide what works in the relationship and simultaneously to avoid what does not work. Meaning: Based on original meta-analyses, experts deemed nine of the relationship elements as demonstrably effective, seven as probably effective, and one as promising. Next Steps: Future directions are to disseminate these findings to practice communities, to implement them in training programs, and to examine the interrelations of the effective elements of the relationship.