Following the enactment of President Obama’s Affordable Care Act, several states raised their Medicaid eligibility income thresholds, leading to a substantial rise in Medicaid enrollment among low-income adults. Extensive research has investigated the effect of Medicaid expansion on adult healthcare behavior and emergency department (ED) use, but few studies have examined its spillover effects on child ED visits. In this paper, I specifically analyze the effect of Medicaid expansion and parental enrollment on child ED visit frequency and payer composition. Through a difference-in-differences analysis, I find a significant increase in child ED visits in expansion states post-implementation, alongside a rise in the Medicaid payer share for these visits. I suggest that Medicaid expansion may alleviate barriers to ED access but may also contribute to moral hazard and an increase in healthcare-seeking behavior. Policies aimed at increasing primary and preventative care use could improve child health outcomes and reduce unnecessary ED visits.