Functional Analytic Psychotherapy (FAP) focuses on in-session interpersonal behaviours to create meaningful, lasting client change. Central to FAP is its focus on clients’ in-session clinically relevant behaviours (CRBs) and the therapist’s contingent natural and authentic reinforcement strengthens adaptive behaviours while decreasing maladaptive ones. Despite challenges in empirical research due to FAP’s idiographic focus, the available evidence supports its effectiveness in using the therapeutic relationship to facilitate meaningful and lasting change. The future of FAP holds significant promise as it continues to evolve by incorporating advances in Relational Frame Theory (RFT), building on Process-Based Therapy (PBT) principles, and integrating concepts from Interbehaviourism. In addition to innovations which enhance FAP’s efficacy as a therapeutic intervention, a major future direction is extending its principles beyond the therapy setting to address global mental health challenges through the Awareness, Courage & Love (ACL) Global Project. Thus, the ongoing development of FAP carries the promise of not only elevating therapeutic impact, but creating a future where mental and emotional well-being resources are universally accessible.