Objectives: A process evaluation was performed for an intervention aimed at improvement of the management of neuropsychiatric symptoms in young-onset dementia. Data about sample quality and intervention quality was evaluated to better understand internal and external validity. In addition, data about the implementation strategy and factors affecting implementation were evaluated to improve further implementation of the intervention. Design: A model proposed by Leontjevas and colleagues consisting of first-order (validity) and second-order (implementation) data was used. Setting and Participants: Care units delivering specialized treatment and support for residents with young-onset dementia. Measures: A description of the recruitment, randomization procedure, and intervention reach was carried out to determine sample quality. To determine intervention quality, data on satisfaction, relevance, feasibility, and fidelity were collected through a questionnaire and reports logged on the server of the web-based intervention. A description of the implementation strategy was provided. Barriers and facilitators for implementation were collected by a questionnaire and analyzed by deductive content analysis. Results: Care units varied in size and were recruited from different geographical regions in the Netherlands. The informed consent rate of the residents was 87.7%. The majority of the nursing home staff were satisfied with the intervention. However, parts of the intervention were perceived as less relevant for their own organization. The feasibility of the intervention was considered low. The fidelity differed between care units. The implementation strategy did not overcome all barriers. Factors affecting implementation covered 3 themes: organizational aspects, culture of the organization, and aspects of the intervention. Conclusions: In general, our results showed sufficient internal and external validity, warranting further effect analyses. Adaptations to specific steps of the care program should be considered to increase feasibility and sustainability. In addition, integration of the care program into the electronic health records is expected to further improve implementation.