Background/Objectives: Medicare-certified home health agencies are required to offer family caregiver training, but little is known regarding the potential impact of this training on outcomes during home health care. We estimate the proportion of family caregivers assisting Medicare home health patients who have unmet training needs and examine whether these unmet training needs are associated with older adults' risk of acute care utilization during home health care. Design: Observational, nationally representative cohort study. Setting: Linked National Health and Aging Trends Study, Outcome and Assessment Information Set (OASIS), Medicare Provider of Services file, and Medicare claims data from 2011 to 2016. Participants: Thousand two hundred seventeen (weighted n = 5,870,905) community-living Medicare beneficiaries who received home health care between 2011 and 2016. Measurements: Family caregivers' unmet training needs measured from OASIS and Medicare claims; home health patients' acute care utilization (including emergency department use and hospitalization) measured from OASIS. Results: Rates of unmet need for training varied by activity, from 8.2% of family caregivers assisting with household chores to 16.0% assisting with self-care tasks. After controlling for older adult and home health provider characteristics, older adults whose family caregivers had an unmet need for training with any caregiving activity were twice as likely to incur acute care utilization during their home health episode (adjusted odds ratio [aOR]: 2.01, 95% confidence interval [CI]: 1.20–3.38). This relationship held across specific caregiving activities including household chores (aOR: 1.98; 95% CI: 1.13–3.46), medication management (aOR: 2.50; 95% CI: 1.46–4.26), patient supervision (aOR: 2.92; 95% CI: 1.36–6.24), and self-care tasks (aOR: 3.11; 95% CI: 1.62–6.00). Conclusions and Relevance: Unmet training needs among family caregivers are associated with greater likelihood of acute care utilization among Medicare beneficiaries receiving home health care. Identifying and addressing family caregivers' training needs may reduce older adults' risk of acute care utilization during home health care.