This multiple case study investigates conditions influencing the integration of the ecological approach in disease prevention and health promotion (DPHP) programs offered to older adults by local health organizations in Quebec. Scheirer’s (1981) implementation model guided the study of five Centres de Santé et Services Sociaux chosen in line with the ecological dimension of their DPHP programs. Documentary analyses were conducted along with thirty-eight semi-structured interviews among professionals and managers. Three categories of factors were explored: professional, organizational and environmental factors. Results indicate the ecological dimension of programs is influenced by organizational norms, competing priorities, team structure, external partnerships, preconceived ideas regarding DPHP for older adults, along with professional interest and training. These results provide levers for action toward optimizing services offered to the older population through disease prevention and health promotion programs.