Rapid social and economic changes are modifying health care delivery systems and health care financing. These changes require that primary care physicians develop new collaborative approaches to patient care, including a reassessment of relationships with other primary care providers, particularly nurse practitioners. The purpose of this research was to explore and define what constitutes a successful collaborative practice. Open-ended, interactive interviews were conducted with three dyads of physician - nurse practitioner in the ambulatory care setting. Data analysis using the grounded theory method revealed six key elements associated with effective collaborative practice: Communication, competence, autonomy, coordination, trust and personality. This research contributes to clarification of the barriers that hinder a collaborative practice and suggests many benefits derived from such a practice. The findings of the study may inspire other health care providers to enter a collaborative practice to achieve excellence in patient care. Ethical decisions cannot be achieved by a single care provider, but rather require the expertise and unique abilities of both physician and nurse practitioner.