Introduction: Most psychological treatments are administered in a one-to-one therapy format, which has proven effective but has limitations in complex clinical situations. Teamwork can help address these limitations by going beyond the one-to-one therapy approach and involving the client's professional and relational network in therapy interventions to promote and secure change. In this issue of Journal of Clinical Psychology: In Session five effective teamwork practices are presented illustrating how clinicians integrate teamwork into treatment delivery to improve outcomes in an array of cases presenting high complexity. Purpose: In this commentary section, we describe the role and essence of these teamwork practices from a systems thinking approach as a theoretical umbrella to understand the diversity of processes hindering and facilitating effective teamwork. Conclussion: From this approach we discuss the core skills that psychotherapists should train to master team working and interprofessional collaboration. The basic professional competence consists in the ability to foster and coordinate shared frames of understanding in case formulation. An advanced systemic skill is based on the ability to formulate and change relational patterns, given that interpersonal processes are the main key factor to understand barriers and facilitators of effective teamwork to overcome stalemated complex clinical situations.