This paper presents a behavior analytic understanding of the functiona
l components of the therapeutic relationship. Whereas other models of
understanding therapy have offered interpretations of the importance o
f the client-therapist alliance, few have specified mechanisms respons
ible for mediating change that have a foundation in experimental psych
ology. Consistent with the radical behaviorally based Functional Analy
tic Psychotherapy (FAP), we describe, using a contemporary understandi
ng of verbal behavior, how the therapist establishes him or herself as
a provider of social reinforcement in order to shape change using con
tingent and noncontingent responding. We propose a reason why a limite
d amount of client-therapist contact can produce large changes in beha
vior. The paper closes with a description of a research strategy for e
valuating the proposed model of effecting client change as a function
of the therapeutic relationship.