This multiple case study examines the transition of four individual cases from new nurse practitioner to primary care provider in the setting of a federally qualified health center. It explores the impact of the country's first residency training program for family nurse practitioners on that transition. Transition theory as developed by Meleis, Sawyer, Im, Messias, and Schumacher (2000) provides a theoretical framework for the exploration of the nature of the transition, transition conditions, and the process and outcome indicators of a healthy transition. Yin's (2009) multiple case study methodology was followed. Data sources included residency application essays, reflective journals submitted throughout the residency, interviews with each case, and interviews with each case's current clinical supervisor and an organizational leader. Summary evaluation data completed by the cases during and at the end of the residency program were examined. Individual case studies and a multiple case cross-case synthesis were developed. Although the number of cases is small, the study findings document commonalities in the cases' transition that offer guidance to organizations and policy makers concerned with assuring an expert primary care provider workforce. Key findings include the following: these family nurse practitioners voluntarily entered the residency program with awareness of their future goals and a desire to develop mastery in the care of very complex, underserved patient populations of all ages. They substantially achieved this goal by the end of the residency or within the first months of practice following the residency. They had anticipated managing complex patients, but were unprepared for the prevalence and impact of co-existing mental illness and/or substance abuse. Facilitating factors for the transition included the program elements of precepted clinic sessions, didactic teaching sessions, being on-call, and certain specialties like psychiatry, women's health, and HIV/hepatitis C. Inhibiting factors cited included confusion about the role of preceptors and residents, and insufficient dedicated support staff resources. The final indicators of a healthy transition are mastery and fluid integrative identity. Data indicates that all cases have completed a healthy transition. This study provides the first data to guide the development of residency training programs for family nurse practitioners in federally qualified health centers.