Most studies that enroll individuals with dementia require a study partner for each participant. Study partners—usually family members—perform several key roles: accompanying the participant to visits, providing information about the participant, and assisting with procedures such as taking medication. Little is known, however, about their experiences when performing these roles. Dementia researchers and institutional review boards need to know these experiences because the study partner role is one key factor in a study’s success. This prospective qualitative study, using up to three semi-structured interviews with 62 study partners involved in a range of dementia studies, documented their subjective experiences. Content analysis demonstrates that study partners perform a range of tasks—often within the context of being a caregiver—that enable cognitively impaired individuals to participate in dementia research. These tasks present study partners with unique burdens and benefits, some of which dementia researchers and institutional review boards can address.