As of September 23, 2010, the Affordable Care Act (ACA) mandated that health insurance plans were no longer permitted to exclude children because of a pre-existing health condition. This paper uses data from the National Health Interview Survey (NHIS) to evaluate the impact of the ACA on health insurance coverage and access to health care for children affected by the ACA’s new provision. We used a difference-in-differences regression analysis to compare changes in health insurance coverage and access to health care before and after the mandate, for children with (n=15,661) and without a chronic health condition (n=50,835). All models controlled for demographics, health status, socio-economic status, region and quarter of interview. Separate regression models were estimated for infants and toddlers (0-3 years), young children (4-11 years) and adolescents (12-17 years) because the health profile and insurance options of children differ substantially by age. Overall, we found that private health insurance continued to decline and public health insurance increased during the study period.  However, insurance purchased on the individual market (the market segment most affected by reform), significantly increased by 1.6 percentage points (p<0.05) for adolescents with chronic health conditions, relative to the trend for adolescents without a chronic condition. Accordingly, adolescents with chronic health conditions also experienced a differential change in delayed and forgone care due to cost, by 3.3 percentage points (p<0.001) and 1.9 percentage points (p<0.05) respectively. Similar results were not found for toddlers or young children.  Results are robust to model covariates and alternative control groups. This study provides suggestive evidence that banning pre-existing condition exclusions in the ACA improved access to health insurance and medical care for adolescents with chronic health conditions. Providing health insurance to children is an important health policy goal, as coverage improves childhood health and prevents early mortality.  We suspect that our results represent a lower-bound for the effect of pre-existing condition rules that took effect in January 2014 because the 2010 mandate lacked a community rating provision and thus coverage for many children in our sample likely remained unaffordable.