Whole home retrofits aim to address the biggest residential energy issues. Their number has grown in recent years along with contractor and program experience in delivering successful retrofits. However the demand for these programs and their participation rates have not grown as much, and many of them fail to capture the full range of available savings. This report explores the challenges faced by home retrofit programs and describes the best strategies for improving project-level realization rates. Programs can achieve even higher savings by coupling these strategies with emerging practices such as home energy management systems, HVAC system quality installation, pay-for-performance program approaches, and targeted outreach.