Physical inactivity and unhealthful diet are major risk factors for noncommunicable diseases, and strategies worldwide now focus on improving diet and encouraging physical activity (PA). Participation in PA lowers the risk for numerous chronic diseases, while a healthful diet also offers resistance to disease. However, practicing both behaviors offers greater protection than practicing either behavior alone. Research evaluating the relationship of diet and PA has focused primarily on nutrients or food groups. Little research exists on PA and overall diet quality, and no research has used the Healthy Eating Index 2005 (HEI-2005) to assess diet quality in healthy young adults, the objective of the current study. To this end, a convenience sample of 70 healthy, young adults was recruited from a university community in 2005-2006. Dietary intake was measured with 7-d weighed food records and HEI-2005 scores were computed to assess diet quality. PA was obtained from 7-d activity records accounting for all minutes of each day. Linear regression models were used to assess the association of HEI-2005 scores to participation in moderate- and vigorous-intensity PA. In this sample, HEI-2005 scores increased as weekly minutes of PA increased (p=0.006, B=0.007). When PA was examined categorically, only the VeryHighPA (≥841 min/week) group had diet quality scores significantly higher than the LowPA (≤420 min/week) group, independent of age, BMI, and gender (p=0.033, B=7.987). Further studies are warranted to clarify the relationship of these health behaviors, an especially important topic as prevalence of obesity and chronic disease continues to rise. / Graduation date: 2013