Objective: Changes to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) occurred in 2009 when supplemental foods offered through the programme were updated to align with current dietary recommendations. The present study reports on a new index developed to monitor the retail environment's adoption of these new food supply requirements in New Orleans. Design: A 100-point WIC Availability Index (WIC-AI) was derived from new minimum state stocking requirements for WIC vendors. A sample of supermarkets, medium and small food stores was assessed in 2009 before changes were implemented and in 2010 after revisions had gone into effect. WIC-AI scores were utilized to compare differences in meeting requirements by store type, WIC vendor status and year of measurement. Setting: Supermarkets, medium and small WIC and non-WIC food stores in New Orleans, Louisiana, USA. Results: At baseline supermarkets had the highest median WIC-AI score (93·3) followed by medium (69·8) and small food stores (48·0). Small WIC stores had a higher median WIC-AI score at baseline than small non-WIC stores (66·9 v. 38·0). Both medium and small WIC stores significantly increased their median WIC-AI scores between 2009 and 2010 (P < 0·01). The increased median WIC-AI score in small food stores was largely attributed to increased availability of cereals and grains, juices and fruit, and infant fruit and vegetables. Conclusions: The WIC-AI is a simple tool useful in summarizing complex food store environment data and may be adapted for use in other states or a national level to inform food policy decisions and direction. (1) . Potential WIC recipients must be pregnant, breast-feeding or less than 5 years of age, meet income requirements and be considered at nutritional risk by a health professional to qualify to receive WIC benefits (1) . In addition to nutrition education and referrals to health care, WIC participants receive monthly vouchers that are redeemed for food items included as part of a WIC food package at one of the authorized WIC food store vendors (2) . WIC has demonstrated positive effects on the birth outcomes of prenatal WIC participants and positive effects on the food and nutrient intakes of participant children (3)(4)(5) . The programme has expanded over the years and currently serves over 10 million women and children (6) . While malnutrition and food security remain an issue with 14·5 % of American households experiencing food insecurity in 2010 (7) , the most recent estimates indicate that 68·0 % of American adults (8) and 31·8 % of American children (9) are overweight or obese. A combination of factors including advances in nutrition information, changes in dietary patterns, expansion of the WIC programme and increased