This article examines (i) how retailers position private label products,(ii) why private labels are sold in some product categories but not in others,and why some national brand products may have difficulty in accessing retailers' shelves,(iii) why some private label products are positioned as "premium" brands,and (iv) how consumers' surplus and total welfare are affected by private labels.We find that private label positioning leads to less differentiation in product category,which structurally changes a retailer's product line in return.Consumer welfare and total welfare are lower