Background: Dietary intake is known to influence human metabolism in ways that can affect health. The Special Supplemental Women, Infants, and Children program (WIC) is a population-based program aimed at improving nutrition and reducing health disparities among pregnant women and children. There is a paucity of research about diet quality in WIC that could optimize maternal and child health outcomes. Purpose: The purpose of this study was to describe diet quality of pregnant women receiving WIC food supplementation and estimate how much WIC food components contribute to quality of the diet. Methods: The study population was drawn from a large federally funded study examining the influence of diet on the vaginal microbiota and preterm birth (Birth, Eating and the Microbiota Study-BEAM: NR014826). A sub-group of 63 women enrolled in the WIC program formed the cohort for this study. An image-based dietary intake method called FoodFotoTM was used to capture nutritional intake. Diet quality was estimated using the healthy eating index (HEI-2010) representing conformance to Dietary Guidelines for Americans. Three-digit food codes aligned to the Food and Nutrient Database for Dietary Studies were used to quantify the density of WIC approved foods in participants diets. Results: The HEI scores for the sample ranged from 32.2 -71.3 (x50.8, SD=9.7). Food components scores for total vegetables, greens and beans, dairy, seafood plant protein and fatty acid ratio exceeded the 50th percentile. Inversely, low scores for sodium and refined grain scores demonstrated high consumption. Regression analysis showed that for every 1% increase in the proportion of WIC approved foods in the diet there was a corresponding increase of 0.65 points to the total HEI score (t=.6.86 (1, 61), P=.001). Conclusions: The mean HEI score for this study was consistent with other studies. The study findings support the hypothesis that the WIC food supplement significantly improves diet quality among the pregnant women enrolled in the program.