Older adults with disabilities rely on support from family caregivers, medical professionals, and paid caregivers. Unlike team-based interprofessional care, coordination of care work is not protocolized or well understood. To describe family caregiver experiences coordinating care with medical professionals, other family caregivers, and paid caregivers. This cross-sectional analysis of the 2023 National Health and Aging Trends Study and the linked National Study of Caregiving included data on 2811 family and unpaid caregivers to community-living adults aged 65 years or older with disabilities. Caregiver characteristics, caregiving circumstances, negative consequences, supportive services use, and, for medical professionals, frequency of interactions and types of communication behaviors. Adapted relational coordination index (RCI; range, 1-5; greater values indicate higher relational coordination) reflecting frequency of any communication and problem-solving communication, as well as shared goals, shared knowledge, and mutual respect with medical professionals, paid caregivers, and other family caregivers. Among a weighted sample of 2811 family and unpaid caregivers (1633 women [63.4%]; 1044 aged ≥65 years [41.5%]), most (2448 [87.6%]) engaged in care work that involved medical professionals (2061 [76.4%]), other family caregivers (1791 [62.8%]), or paid caregivers (822 [23.2%]). Relational coordination was reported to be weak with medical professionals (RCI, 3.10 [95% CI, 3.03-3.16]) and moderate for paid caregivers (RCI, 3.80 [95% CI, 3.71-3.89]) and other family caregivers (RCI, 4.20 [95% CI, 4.13-4.27]). Across all roles, relational coordination was higher when caregivers were related to the older adult, assisted an older adult with greater care needs, and engaged in higher-intensity caregiving. Use of supportive services was associated with higher relational coordination with medical professionals and paid caregivers but varied in magnitude by service type; the greatest differential was observed for family caregivers who did (vs did not) receive training when reflecting on medical professionals (3.63 [95% CI, 3.42-3.83] vs 3.05 [95% CI, 2.99-3.12]; P < .001). The RCI fluctuated from 2.33 [95% CI, 2.24-2.42] among caregivers who never interacted with medical professionals to 4.21 [95% CI, 4.11-4.31] among caregivers who interacted with medical professionals often and were always or usually asked about needed help. This cross-sectional study of a national survey found that few family caregivers engage in care work alone. Further study is needed to determine if weak relational coordination with medical professionals may be remediated through training and supportive communication.