Background and Objectives: The ProMuscle in Practice intervention combines resistance exercise training and dietary protein intake for community-dwelling older adults, implemented by health care professionals (HCPs). This study aimed to evaluate implementation and context of this intervention in Dutch health care practice. Research Design and Methods: We conducted a randomized controlled multicenter intervention study in 5 Dutch municipalities. Eighty-two older adults received the 12-week intensive support intervention (resistance exercise training and individual dietary counseling) and the optional 12-week moderate support intervention (resistance exercise training and a nutrition course). Mixed method data were collected from both participants and HCPs (n = 37) on process indicators recruitment, dose received, acceptability, fidelity, applicability, and context. Results: Overall, the intervention was feasible to implement and accepted by participants and HCPs. About two thirds of participants continued with the moderate support intervention after the first 12 weeks. The mean dose received for the training sessions was 83.6% in the intensive intervention, 63.6% in the moderate intervention, >90% for individual dietitian consultations, and 76.8% for the nutrition course. The intensive support intervention was implemented with high fidelity, whereas for the moderate support intervention resistance exercise trainings varied in implementation between exercise providers. Discussion and Implications: A combined resistance exercise training and dietary protein intervention for community-dwelling older adults can be successfully implemented in practice. Well-tailored interventions, intensive supervision by skilled HCPs, social aspects, fidelity, and fit within real-world settings appeared essential for successful implementation. These elements are important for continuous intervention optimization to accomplish broader and successful implementation.