Developing team-based care models and expanding nurse practitioner (NP) workforce in primary care are recommended by policy makers to meet demand. Little is known how to promote interprofessional teamwork. Using a mixed-methods design, we analyzed qualitative interview and quantitative survey data from primary care NPs to explore practice characteristics important for teamwork. The Interprofessional Teamwork for Health and Social Care Framework guided the study. We identified NP-physician and NP-administration relationships; organizational support and governance; time and space for teamwork; and regulations and economic impact as important. Practice and policy change addressing these factors is needed for effective interprofessional teamwork.