The manualization of a complex occupational therapy intervention is a crucial step in ensuring treatment fidelity for both clinical application and research purposes. Toward the latter end, intervention manuals are essential for ensuring trustworthiness and replicability of randomized controlled trials that aim to provide evidence of the effectiveness of occupational therapy. In this article, we review the literature on the process of intervention manualization. We then illustrate the prescribed steps through our experience in implementing the University of Southern California/Rancho Los Amigos National Rehabilitation Center’s collaborative Pressure Ulcer Prevention Project. In this research program, qualitative research provided the initial foundation for manualization of a multifaceted occupational therapy intervention designed to reduce the incidence of medically serious pressure ulcers in adults with spinal cord injury.