We investigate how a retailer’s private label positioning strategy can contribute to the retailer’s chain equity, in terms of baseline market share and of price sensitivity across product categories. We explore the impact of characteristics of the private-label program on the competition between retailers (chains). We propose a three dimensional measure for the private-label positioning: breadth of the private-label program, price, and assortment size. We include these variables in a two-level model for the retailer’s market share in a particular product category. In the first level of the model we associate chain market shares across categories with prices, marketing-mix variables, and lagged shares. In the second level we link the baseline market shares and the market share price sensitivities with private-label positioning variables and some chain/category control variables. Using the data we specially compiled for this study, we find that private-label positioning has no impact on chain baseline market shares, while it does impact market share price sensitivities.