The effect of common cocklebur interference on snap beans was investigated at Bridgeton, NJ, in 1987 and 1988. Snap bean yields were reduced by increasing weed densities. Yields were reduced 8 to 44% in 1987 and 2 to 55% in 1988 by full-season in-row weed densities ranging from 0.5 to 8/m2. One weed and 4 weeds/m2 were the damage-threshold populations of common cocklebur with full-season interference in 1987 and 1988, respectively. The weed-free requirement, after planting, was to the unifoliolate stage of snap beans. Common cocklebur at 4 weeds/m2 did not affect yield when snap beans were maintained weed free until the unifoliolate stage of snap beans. The critical duration of interference for common cocklebur emerging with snap beans was between the emergence and full-bloom stage of snap beans. Snap bean yield was not reduced with weed removal at full bloom.