A large literature examines the effects of health insurance on the health care utilization of children; however, most existing studies conceptualize coverage as a point-in-time measure rather than as a dynamic phenomenon. The major contribution of this article is its provision of estimates on the relationship between the duration of coverage over the course of a calendar year and health care utilization among children. Using child-level fixed-effects regression, we find that an incremental uninsured month is associated with a 0.7 percentage point decline in the probability of receiving a visit over the course of a year and a 3% decrease in the number of visits received. Children with intrayear coverage losses are more likely than those with continuous coverage to lose their usual source of care, which serves as a potential mechanism through which short gaps in coverage may lead to longer-term decrements in utilization.