A practice-based research network (PBRN) is a group of practices devoted principally to the care of patients and affiliated for the purpose of examining the health care processes that occur in practices. PBRNs are characterized by an organizational framework that transcends a single practice or study. They provide a "laboratory" for studying broad populations of patients and care providers in community-based settings. History of primary care research Before there were research institutes or networks of practices, individual practitioners studied their patients' problems with scientific rigor. Among these were five general practitioners who have been recognized for their seminal work during the past 125 years. They are James Mackenzie, Will Pickles, John Fry, F.J.A. Huygen and Curtis G. Hames. Each of these pioneers demonstrated that important new knowledge could be discovered by practicing family physicians. More recently, practicing primary care pediatricians such as Burtis Breese and William Carey contributed a body of knowledge on child health. These doctors all wondered about their patients' problems and they developed a means of gathering and recording data on their patients. Each of these research pioneers provide inspiration for the development of practice-based, primary care research networks because each demonstrated that important new knowledge could be discovered by the practicing primary care physician. They each wondered about their patients, developed means of gathering and recording data, and found collaborators and support from their staff and local communities. Unfortunately, they practiced in an era that was over-committed to specialism. Research focused on molecular mechanisms of disease. The rush to specialization by the medical community and the linking of research to specialists resulted in decades of neglect of primary care and virtually no recognition of the need to investigate care in the primary care setting. Instead, the common wisdom viewed primary care practices as relatively boring places that could be potential sites of application of the fruits of research done elsewhere in research laboratories, hospitals and institutes. Among the early regional networks started in the 1970s were the Dartmouth CO-OP PBRN in New Hampshire, Family Medicine Information System in Colorado (FMIS) and the Cooperative Information Project. These regional networks learned from each other and succeeded in conducting studies focused on what was happening in primary care. They attracted funding from medical schools, national philanthropic foundations and federal programs such as Health for Underserved Rural Areas. As the 1970s closed, these early networks enjoyed sufficient success to stimulate