ObjectiveTo evaluate the effects of the parent-reported medical home status on health care utilization, expenditures, and quality for children. Data SourcesMedical Expenditure PanelSurvey (MEPS) during 2004-2012, including a total of 9,153 children who were followed up for 2years in the survey. Study DesignWe took a causal difference-in-differences approach using inverse probability weighting and doubly robust estimators to study how changes in medical home status over a 2-year period affected children's health care outcomes. Our analysis adjusted for children's sociodemographic, health, and insurance statuses. We conducted sensitivity analyses using alternative statistical methods, different approaches to outliers and missing data, and accounting for possible common-method biases. Principal FindingsCompared with children whose parents reported having medical homes in both years 1 and 2, those who had medical homes in year 1 but lost them in year 2 had significantly lower parent-reported ratings of health care quality and higher utilization of emergency care. Compared with children whose parents reported having no medical homes in both years, those who did not have medical homes in year 1 but gained them in year 2 had significantly higher ratings of health care quality, but no significant differences in health care expenditures and utilization. ConclusionsHaving a medical home may help improve health care quality for children; losing a medical home may lead to higher utilization of emergency care.