Focusing on caregivers of persons with dementia, we conducted a longitudinal study to examine the effectiveness of a psycho-educational intervention program Remember ME. The program aimed to reduce caregiver stress and improve caregivers’ quality of life. Given the multifaceted nature of dementia care, we used a mixed-methods approach which integrates the strengths of both qualitative and quantitative methodology. In particular, quantitative data were collected to examine caregiver stress and quality of life after a randomized controlled trial with systematic follow-up from baseline to 6 months post-intervention. Qualitative data were collected to understand caregiver perception of Remember ME and dementia caregiving. This case study explains how mixed-methods approach enabled quantitative findings to be clarified and complemented by qualitative data. In addition, we describe and provide advice on running intervention programs and integrating quantitative and qualitative findings.