Although the importance of the therapeutic relationship in cognitive behavioral therapy (CBT) has been recognized from its inception, the nature and role of the therapeutic alliance in CBT on treatment outcomes continues to be studied and debated. This chapter defines the alliance in CBT and reviews the empirical literature investigating the alliance–outcome relationship specifically for anxiety and related disorders. Grounded in the empirical literature, this chapter specifically discusses the importance of the alliance on treatment engagement and outcomes. Practical considerations for optimizing the alliance within the context of anxiety and related disorder treatment are discussed and clinical case examples are utilized to illustrate concepts with a focus on exposure-based protocols.