Objective: Examine the impact of providing yogurt to women enrolled in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Design: Randomized, controlled intervention trial. Setting: Two California WIC local agency sites. Participants: 511 pregnant, breast-feeding, or postpartum women. Intervention: Substitution of part of the WIC milk allowance with yogurt accompanied with educational materials. Main Outcome Measures: Participants' consumption and attitudes regarding yogurt provision. Analysis: Chi-square, Fisher exact, and Student t test to compare pre- versus post-intervention responses. Nonparametric Wilcoxon, chi-square, and t test to compare changes in response in intervention versus controls. Analysis of covariance models to test the influence of language preference on outcomes. Results: Over 86% of women wanted to substitute some of their milk vouchers with yogurt. Among these, 62% reported preferring yogurt to milk. The majority (89%) redeemed the yogurt coupons. Compared to controls, intervention women reported a trend (P = 0.09) toward an increase in yogurt intake of 1.0 fl oz/day while not decreasing other dairy consumption. Those in the intervention group with the lowest tertile of yogurt intake at baseline increased yogurt consumption by 2.8 fl oz/day (P = 0.003) relative to controls with lowest intake. Conclusions: Yogurt is likely to be a popular substitute for milk and could contribute to increased dairy intake among women if it were an option in WIC. (Contains 1 figure and 5 tables.)