This article examines the influence of coupons on private label shares of grocery products. The impact of national brand and private label coupons, distributed by manufacturers and retailers, is examined. A consumer framework and a typology of coupon effects are developed to explain different types of coupon usage behavior. Aggregate scanner panel data on 480 product categories are used in the analysis. Both the type of coupon and the method of distribution (by manufacturer or by retailer) are found to be important determinants of private label share response. Couponing activities by the national brand manufacturer are negatively related to private label share, thus indicating that they may be effective deterrents of private label penetration. However, couponing activities related to private labels do not help increase private label shares. The surprising finding is that national brand store couponing activity is positively related to private label share.