Exercise is effective in preventing falls among older adults. However, few studies have included people living with dementia and their carers and explored their experiences. The aim of this study is to explore what affects the acceptability of exercise interventions to better meet the needs of people with dementia and their carers as a dyad. Observations, field notes containing participant’s and instructor’s feedback, and focus groups with 10 dyads involved in Tai Chi classes for 3 or 4 weeks in two sites in the South of England were thematically analyzed to understand their experiences. Findings suggest that dyads’ determination to achieve the benefits of Tai Chi facilitated their adherence, whereas a member of the dyad’s low sense of efficacy performing the movements during classes was a barrier. Simplifying class content and enhancing the clarity of instructions for home-based practice will be key to support the design of future exercise interventions.