Reviews definitions of the alliance (ALI) concept and proposes 4 relatively independent ALI dimensions that are complementary and compatible. These include (1) the therapeutic ALI, (2) the working ALI, (3) the therapist's empathic understanding and involvement, and (4) the patient–therapist agreement on the goals and tasks of treatment. There is evidence to support the predictive validity of the ALI in psychotherapy, with observations available across a variety of psychotherapy approaches, symptomatic disorders in outpatient samples, and sources of information (patient, therapist, clinical judges). A lack of association between ALI and outcome was, however, observed in some studies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)