Background: People with developmental disabilities experience worse health than typically developing peers. This health differential is often described in terms of health disparities, which refers to differences caused or exacerbated by social or access issues. Objective: the goal of this study was to compare the weight status and health conditions of adults with Down syndrome to comparison groups of adults with developmental disabilities and adults with no disability. Methods: Information about health risks and health conditions was collected for 291 adults with Down syndrome living in Ohio through an online survey. We compared this data on adults with Down syndrome to state-level data from adults without disabilities (2012 BRFSS) and Ohio data on a random sample of adults with developmental disabilities other than Down syndrome (2012-2013 National Core Indicators). Results: Adults with Down syndrome were 3 times more likely to be overweight or obese than adults without disabilities. Surprisingly, despite having a body mass index in the overweight or obese range, 70% of adults with Down syndrome reported having eating habits that were good to excellent and less than 6% of the Down syndrome sample reported having co-occurring diabetes or hypertension. Discussion: Despite high rates of overweight and obesity, few adults with Down syndrome reported having the chronic health conditions associated with excess weight. Further research is needed to understand the health risks of overweight in adults with Down syndrome and the availability of health promotion programs for this population.