We examined market commonality and product mix similarity as predictors of competitive response by small retail hardware stores to their nearest “Big Box” competitor. Data from 314 small retail hardware stores revealed a consistent relationship between greater market commonality and small firm responsiveness. However, no consistent relationship was observed between resource similarity and responsiveness. Tests for interactions between these two predictors were inconsistent—two (of five) specific product categories (i.e., hardware and tools, seasonal goods) were significant but in divergent patterns. We discuss what these findings suggest concerning the competitive interaction between small retailers and their Big Box rivals.