There are over five million people in the United States living with dementia. Most live at home and are cared for by family. These family caregivers often assume care responsibilities without education about the disease, skills training, or support, and in turn become at risk for depression, burden, and adverse health outcomes when compared to non-dementia caregivers. Despite over 200 caregiver interventions with proven benefits, many caregivers lack access to these programs. One approach to enhance access is to embed evidence-based caregiver support programs in existing community-based services for people with dementia such as adult day services (ADS). Here we describe the protocol for an embedded pragmatic trial designed to augment standard ADS known as ADS Plus. ADS Plus provides family caregivers with support via education, referrals, and problem solving techniques over 12 months, and is delivered on-site by existing ADS staff. Embedding a program in ADS requires an understanding of outcomes and implementation processes in that specific context. Thus, we deploy a hybrid design involving a cluster randomized two-group trial to evaluate treatment effects on caregiver wellbeing, ADS utilization, as well as nursing home placement. We describe implementation practices in 30 geographically and racially/ethnically diverse participating sites. Clinical trial registration #: NCT02927821.