This paper examines the effect of WIC program Participation on food consumption and diet quality of U.S. children between 2 and 4 years of age. Diet quality is assessed using the Healthy Eating Index, U.S. Department of Agriculture's instrument for measuring overall diet quality incorporating ten recommended components of dietary guidelines. The study has found that WIC program participation has significant positive influence in improving diet quality as measured by HEI and several of its components. The analysis has also indicated that the WIC program has significant positive influence in reducing sugar consumption by children. This research and the results presented have potential significance for researchers, economists and policy makers focusing on the determinants of children's diets and the role of Federal food assistance and nutrition education programs.