The objective of the study was to assess the relationship between participation in the Expanded Food and Nutrition Education Program (EFNEP) and food-related behavior change, as measured by the Healthy Eating Index (HEI)-2005, using a single-state, case study approach. Pre-EFNEP and post-EFNEP participation HEI scores as well as demographic, geographic, socioeconomic, and program participation characteristics from fiscal years 2013-2016 were analyzed using summary statistics and Ordinary Least Squares regressions. HEI scores were adjusted for age, sex, race, rural/urban residence, county, highest grade achieved, income, number of children, public assistance programs, and number of hours in EFNEP in the analysis. The total HEI score and several HEI subscores improved from pre-EFNEP to post-EFNEP at the 5% significance level or better. Sodium and total grains scores decreased post-EFNEP: P = .003 and P = .05, respectively. Participation in Women, Infants, and Children or the Supplemental Nutrition Assistance Program had no effect on HEI scores or changes in scores post-EFNEP. Spending less than 7 hours in the program was associated with a smaller improvement in total HEI score ( P = .05) and an increased intake of sodium ( P = .03), compared with spending 7 to 16 hours in the program. Overall, EFNEP participation was associated with improvements in diet quality.