This article presents the results of an assessment of HIV/AIDS in-service training provided to Nigerian health workers through funding from the US President’s Emergency Plan for AIDS Relief (PEPFAR). CapacityPlus conducted the assessment with an online survey tool developed using the In-Service Training Improvement Framework. A total of 39 partners providing PEPFAR-funded in-service training in Nigeria completed the survey. The survey captured the landscape of the types of training provided; the cadres of health workers receiving training; and the processes, procedures, and resources used by partners over the period January 2007–July 2012. Based on the findings, the authors make a number of recommendations for increasing the effectiveness of HIV/AIDS in-service training in Nigeria.