Background: The Grip on Challenging Behavior care program for managing challenging behavior was implemented in the dementia special care units of 17 Dutch nursing homes. A process evaluation of the implementation of the care program was performed to determine the quality of the implementation and the lessons to be learned for future implementation.Methods: The care program was implemented according to a stepped wedge design. First-order data (data on recruitment, reach, relevance and feasibility) were used to determine the validity of the study, and second-order data (intervention quality and the barriers and facilitators for implementing the care program) were used to describe the implementation process. Two structured questionnaires were administered to care staff and key stakeholders and semi-structured interviews were held in the units.Results: University affiliated and non-affiliated nursing homes from different parts of the Netherlands participated. The resident participation rate was over 95% and the participation rate for the training sessions was 82%. Respondents considered the care program relevant and feasible. The degree of implementation was not optimal. The barriers and facilitators in implementing the care program could be divided into three categories: organizational aspects, culture on the unit and aspects of the care program itself.Conclusions: The recruitment, reach, relevance and feasibility are sufficient to allow for analysis and generalization of the effects of the care program, but the degree of implementation should be taken into account in further analysis. Future projects that involve implementation should consider the specific features of the organization and the cultural orientation of the unit to better adapt to specific needs.Trial registration: The Netherlands National Trial register under number NTR2141 registered on 11 December 2009. Randomization took place in November 2010, and the first intervention group started using the intervention in February 2011.