Accessing health services at an early age is important to future health and life outcomes, yet little is currently understood on the role of insurance in facilitating access to care for children. Exploiting a regression discontinuity design made possible through a policy to provide health insurance to pre-school aged children in Vietnam, this paper evaluates the impact of health insurance on the health care utilization outcomes of children around the eligibility threshold of six years. Using three rounds of the Vietnam Household Living Standards Survey, the study finds a positive impact on inpatient and outpatient visits and no significant impact on expenditures per visit at public facilities. We find moderately high use of private outpatient services for children under the age of six and no evidence of a switch from private to covered public facilities under insurance. Results suggest that adopting public health insurance programs for young children may be an important vehicle to improving service utilization in a low- and middle-income country context. Challenges remain to ensure that adequate protections are provided from the costs and other barriers to care.