This chapter explicates the broad context of psychotherapy integration and sets the stage for the subsequent chapters in the volume. This chapter offers a primer on integration: in the dual sense of a primer (soft i) as a small introduction to the subject and of a primer (hard i) as a basecoat or undercoat for the following applications. This chapter begins by describing the converging reasons for the growth of psychotherapy integration, after which it reviewsfour predominant routes to integration. This segues into a brief consideration of the varieties of integration, which includes summaries of recent studies on the prevalence and subtypes of eclectic/integrative therapies. The chapter concludes with a discussion of recurrent obstacles to psychotherapy integration.