This paper uses data from an ongoing panel study of urban youth to examine the causes and correlates of hidden gun carrying among young urban males. The analysis assesses the changing impact of gang membership, drug sales, and peer gun ownership for protection on gun carrying at nine separate points over the early adolescent to young adult life course. In early adolescence, gang membership is a strong motivation for gun carrying. At somewhat older ages, drug dealing, particularly high drug sales, and illegal peer gun ownership replace gang membership as the primary determinants of illegal gun carrying.