For many years, nonphysician clinicians (NPCs) have participated in the care of patients. However, their numbers were small and their licensed prerogatives were narrow. Over the past decade, these characteristics have changed in three important ways. First, training in many of the NPC disciplines has increased substantially, and the growth of these disciplines is accelerating. Second, state laws and regulations have expanded both the practice prerogatives of NPCs and their autonomy from physician supervision. Third, payers have increased their access to reimbursement. As a consequence, NPCs are undertaking many elements of care that previously were provided by physicians. Their participation is generally cost-effective and is met with a high degree of patient satisfaction. This presents both opportunities and challenges to physicians as they forge new relationships with NPCs and as their own spectrum of responsibilities evolves.