Traditionally, the addiction literature has focused on male drug users and less attention has been given to female users. More recently, research investigating gender differences in drug use and associated problem behaviors has emerged. This article contributes to the growing research base by drawing on data collected from structured interviews with 2,682 male and 453 female arrestees conducted as part of the New English and Welsh Arrestee Drug Abuse Monitoring (1999-2002) program. Clear gender differences in drug use and associated behaviors are identified. Women were found to be more serious drug users and to experience more associated problems than men. The research and policy implications of the research are discussed and the study's limitations are noted.