A nationwide survey of supermarket prices and other store, firm, and city characteristics found considerable diversity between cities and among stores and firms within cities in 1982. Store size, sales volume, store services, occupancy costs, market growth, and market entry contributed to price differences between supermarket firms. Differences in market concentration, firm market share, and firm labor costs were not significant determinants of supermarket prices. Considerable switching occurred in the price rankings of firms in most cities over the three survey periods.