The Home Performance with ENERGY STAR Program (HPwES) was established to promote a comprehensive, whole-house approach to retrofits. It is currently administered by the U.S. Department of Energy (DOE) after being jointly administered by DOE and the U.S. Environmental Protection Agency (EPA) since the Program's inception in 1999. This paper presents the results of a process evaluation of the HPwES Program. Interviews were conducted with key federal Program administrators and a sample of sponsors and contractors responsible for implementing the Program in the field. The respondents describe a program whose success is largely dependent on the use of the ENERGY STAR brand and the flexibility given sponsors to tailor their programs to their specific contexts. It is recommended that the HPwES Program: evolve to better meet the needs of specific types of sponsors (e.g., utilities, public benefit funds); implement a national marketing campaign; create closer ties to other DOE programs (e.g., the Weatherization Assistance Program); and conduct research to better establish program energy savings impacts and awareness. (C) 2013 Elsevier Ltd. All rights reserved.