Leisure activities are important to maintain and improve health in old age. To better understand what older people want to do when participating in an adult day program, it is important to systematically assess their leisure activity preferences. Yet, at present, there is no instrument for this purpose. This protocol describes plans to modify or develop, and test psychometrically, an instrument to assess leisure activities preferences for adult day services. Steps include: identifying leisure activities through literature review and an evidence map; categorizing activities and creating a concept map based on input from adult day participants; and adapting the PELI-D or another tool to assess preferences for leisure activities in adult day services. The last step is to test the resulting instrument psychometrically.