With a traditional focus on primary care or selected patient populations, advanced practice nurses (APNs) are forging new roles in a variety of practice settings, including acute and critical care. APNs have become important members of the critical care team, yet the impact of their care on acute and critically ill patients has not been well studied. This article presents an overview of the research currently available on outcomes of APN practice for acute and critically ill patients. The findings from these studies are discussed and implications for the future of APN outcomes research are provided.