BACKGROUND: Peripherally inserted central catheters (PICCs) and midline catheters are often placed by nurse-led vascular access teams (VATs). While some data regarding the effectiveness of these teams exists, less is known about their structure and function. OBJECTIVES: To examine the roles, functions, and composition of VATs related to the use and management of PICC and midline catheters. METHODS: A descriptive, multi-method study that included an online survey of 62 hospitals participating in a quality improvement consortium and qualitative interviews with 74 hospital-based clinicians in 10 sites. Interviews were recorded, transcribed, and analyzed using a rapid analysis and matrix approach. The survey, which contained closed-ended, categorical questions, was analyzed using frequencies and percentages. RESULTS: More than 77% (n = 48) of hospitals had an on-site VAT. The average team size was seven nurses; their primary function was device insertion. Interview findings revealed that teams varied in characteristics and functions. Interviewees described the broad role that teams play in device insertion, care and removal, and in educating/training hospital staff. However, we found that teams' role in decision making, particularly related to appropriate device selection, was limited and, in some cases, met with physician resistance. CONCLUSIONS: To realize the full benefit of VATs, changes in hospital culture, along with an increased willingness from physicians to integrate VAT nurses in decision making, may be needed. Future interventions aimed at engaging and empowering teams appear necessary.