Demands for critical care services are increasing, but the supply of qualified physicians is not. Moreover, there are mounting national expectations for continuous on-site, senior providers and for adherence to quality and safety practices. In teaching institutions, manpower shortages are exacerbated by shrinking trainee duty hours, and there is a growing desire to recoup the revenue lost when a non-credentialed provider delivers a service. Increasingly, hospitalists and acute-care nurse practitioners (ACNPs) are meeting these needs. This article describes the development of an ACNP service in a university hospital medical intensive care unit (ICU) designed to improve the range and quality of services and faculty staffing when the ICU expanded from 22 to 34 beds without adding physicians. Eight ACNPs were hired and, over 9 months, received didactic, procedural, simulation center, and supervised patient care training. Progressive workload and graded responsibility were used to transition to a 24-hour, in-house, resident-independent, attending-supervised service, which now admits just under half of all patients (3.4 ± 1.3 patients/day), cares for approximately one-fourth of the unit's critically ill patients (6.0 ± 1.4 patients/day), and responds to medical rapid response team calls daily (1.5 ± 1.7 calls/day). Over the first 5 months of operation, work output in all categories continued to increase, with ACNPs documenting an average of 11.1 ± 2.7 activities per day (all data mean ± standard deviation). Acute-care nurse practitioners also provide 40% of the daily resident core lectures and a monthly staff nurse conference. Insufficient data exist at this time, however, to report accurate billing or collection results. Specific areas discussed within this article include service structure, hiring and training, implementation, scheduling, supervision, problems encountered, productivity, monitoring, and future plans.