Abstract Background and Objectives Sustained implementation of new programs in complex care systems like nursing homes is challenging. This prospective qualitative evaluation examined factors affecting the sustainability of the Staff Training in Assisted Living Residences in Veterans Health Administration (STAR-VA) program in Veterans Health Administration (VA) Community Living Centers (CLC, i.e., nursing homes). STAR-VA is an evidence-based interdisciplinary, resident-centered, behavioral approach for managing distress behaviors in dementia. Evaluation Design and Methods In 2019, we conducted 39 semistructured phone interviews with STAR-VA key informants across 20 CLCs. We identified a priori themes based on the Organizational Memory Framework, which includes 7 Knowledge Reservoirs (KRs): people, routines, artifacts, relationships, organizational information space, culture, and structure. We conducted content-directed analysis of transcripts to identify factors to program sustainment. Results We identified 9 sustainment facilitators across KRs: engaged site leaders and champions, regular meetings and trainings, written documentation and resources, regular and open communication, available educational tools (e.g., handouts and posters), adequate spaces, leadership support on many levels, staff buy-in across disciplines, and staff competencies and recognition. Ten barriers across KRs included: staffing concerns, inconsistent/inefficient routines, inconsistent documentation, lack of written policies, communication gaps, nonstandardized use of tools, constraints with meeting spaces and regulations on posting information, limited leadership support, division among staff, and missing performance expectations. Discussion and Implications Findings inform tailored strategies for optimizing STAR-VA program sustainment in CLCs, including the development of a sustained implementation guide, implementation resources, regional communities of practice, and STAR-VA integration into national CLC quality improvement routines for team communication and problem-solving.