Functional family therapy (FFT) is an integrated model that combines family systems and cognitive behavioural theories into a coherent relationship-based approach for working with young persons with externalizing problems and their families. FFT is an evidence-based model that has been supported in numerous controlled research studies and community-based evaluations. In-session process research has also shed light on the clinical interior of treatment, and findings from this research have helped shape the articulation of the core principles and techniques of the model. FFT proceeds through five distinct phases of treatment: engagement, motivation, relational assessment, behaviour change and generalization. Each phase has specific goals, focus, activities and skills. The principles of FFT are consistent with many of the features of core competencies approaches in cognitive behavioural therapy. In this chapter, we describe research on FFT that has led to the inclusion of elements that are considered core competencies. A detailed overview of the FFT clinical model is provided, as are specific examples of techniques or clinical focus that are consistent with a core competencies framework.