Supermarket companies expend significant resources and employ many promotional activities so as to convince consumers to shop their stores. This analysis investigates the promotional activities of a single retail food company to determine the price and promotion responsiveness of fluid milk products that differ by milkfat content. It utilizes weekly, store-level scanner data. Seasonality and advertising are significant determinants of retail sales of fluid milk. Own-price elasticities are negative, and cross-price elasticities are positive for all milk types and are significant and elastic in the case of 2% milk. Advertising effects are positive and statistically significant. The response to advertising is much more pronounced for reduced-fat milk types than it is for whole milk.