This study tests whether a tailored, fully asynchronous online group intervention (VOCALE LBD) reduces depression in family caregivers of people with Lewy Body Dementia (LBD), compared to standard educational materials. LBD is the second most common form of degenerative dementia and causes distinct challenges, including visual hallucinations, REM sleep disorder, and severe motor symptoms, that are not addressed by generic caregiver interventions. Depression rates in LBD caregivers reach 40-50%, double the rate seen in Alzheimer's disease caregivers, yet no rigorous digital interventions exist specifically for this population. VOCALE LBD is a text-based, low-bandwidth platform (Discourse) that brings groups of 10-15 caregivers together in an 8-week moderated online community. Weekly topics address LBD-specific challenges (sleep problems, hallucinations, self-care) and problem-solving skills using the ADAPT method. A pilot study (n=54) showed strong effects on depressive symptoms (Cohen's d=0.54 at 1-month follow-up), near-perfect engagement, and high participant satisfaction. This RCT (N=220) will test efficacy, examine mechanisms of action (self-efficacy and problem-solving), and explore analytics approaches for pragmatic monitoring, laying groundwork for future implementation in clinics and community organizations.