Clearly there are many (and increasing) group therapies which have amassed evidence. Despite theoretical differences, there are factors common to all group therapies, such as group therapeutic relationships. Group therapeutic relationships refer to all relationships introduced and fostered by group treatment. These relationships occur between group leaders and group members, between group members, and between group members and the group as a whole. Together, therapeutic relationship factors affect the outcome of group therapy more than the theoretical orientation or type of therapy being offered (Burlingame & Strauss, 2021; Burlingame et al., 2018; Alldredge et al., 2021). Therefore, establishing and maintaining therapeutic relationships within the group is an essential component of evidence-based practice. Yalom and Leszcz (2021, p. 3) emphasize that “building cohesive groups and strong relationships” is one of “the hallmarks of the evidence-based group therapist.”

Two group therapy constructs which have amassed enough research to merit pages of their own are alliance and cohesion. Specific definitions, evidence, and resources for these constructs will be available on the respective pages. These pages will be created during Phase II of the Evidence-based Group Treatment Website project.