Purpose: The article seeks to identify patterns of service utilization among informal caregivers of frail older adults. In particular, the study examined determinants that explain heterogeneous variations in caregivers' service use patterns. Methods: Using a latent class analysis (LCA) on the 2004 National Long-Term Care Survey and Informal Caregiver data (n = 1,908), this study classifies overall patterns of caregiver service utilization: financial information, support group, respite service, day care or senior center, personal or nursing care, housework, meal delivery, transportation, house modification, and assistive devices. With an emphasis on caregivers' service use patterns and social network derived from the Network Episode Model, the modified Andersen model guides determinants of these patterns. Results: The LCA classified a hierarchical structure of service use patterns: multiple service users, selective in-home service users, and light service users. Caregivers' network compositions signified heterogeneity in service use patterns. Care recipient- and caregiver-related needs contributed to distinguishing service use patterns. Implications: Differentiation of services may be important for meeting caregivers' needs and distributing program resources by identifying target populations for intervention. This typology process may tailor specific interventions to better support caregivers.