This article examines the past, present and future of primary care and teamwork. It begins with a definition and description of primary care–its uniqueness, diversity and complexity, including the historical role of teams within primary care. The article then reviews the emergence of innovative primary care teams, including those grounded in new processes such as the Patient-Centered Medical Home and interprofessional teams that include new types of health professionals, particularly psychologists and other integrated behavioral health clinicians. The article describes key factors that support or hinder primary care teamwork, as well as evidence of the impact of these team-based models on patient outcomes, costs, and team members. It also discusses the role of primary care teams within multiteam systems (or ‘teams of teams’), which are organized around the needs of patients and families, and the unique challenges these systems pose to coordinating care. The article concludes with recommendations for advancing teams in primary care, including changes in payment, descriptions of team competencies, models for primary care team training, and research necessary to inform the gaps in scientific knowledge.