Objectives: This study describes the process evaluation of the experience sampling method (ESM) intervention ‘Partner in Sight’ for spousal caregivers of people with dementia. The aim was to determine internal and external validity of the intervention and provide information for future implementation in clinical practice. Method: Qualitative and quantitative data on sampling quality (recruitment and randomization, reach) and intervention quality (relevance and feasibility, adherence to protocol) were evaluated using descriptive statistics and conventional content analysis. Results: The participation rate included 31.4%. Due to recruitment difficulties and time constraints the original goal to include 90 caregivers was not met. The intervention was largely performed according to protocol and well received by the participants. Overall, the ESM-derived feedback was considered supportive and increased participants’ awareness of their feelings and behaviour. A large variance was found in the extent to which caregivers applied the feedback into their daily lives. The importance of the personal coach to provide face-to-face feedback and stimulate caregivers to implement new insights into their daily lives was emphasized. Suggestions for improvement were to reduce the time intensity of the programme, to better tailor the programme content to one's personal situation, and to improve the ESM device. Conclusion: Although recruitment barriers were encountered, results indicate that future implementation of the ESM intervention ‘Partner in Sight’ is likely to be feasible in regular health care. If the intervention turns out to be (cost-) effective, a fine-tuned version of the programme could be a valuable addition to the current health care system.