This study allocated 201 (nearly) daily users of heroin and/or crack into four groups, depending on their addiction care participation. Earlier studies have compared treatment groups and nontreatment groups. In this study the treatment group is divided into three categories: (1) drug users in contact with only treatment agencies--i.e., methadone maintenance, clinical and ambulant drug treatment; (2) drugs users in contact with only care agencies--i.e., day and night shelters and drug consumption rooms, which have no explicit aims to change patterns of drug use; and (3) drug users in contact with both treatment and care agencies. This allocation intro three different groups fits the notion of harm reduction, one of the policy aims in The Netherlands. The fourth group consists of drug users in contact with neither treatment nor care agencies. The results show that it is useful to distinguish these four categories, instead of two. The four groups are different from each other with respect to some of their characteristics (e.g. debt situation, prostitution, homelessness) and their drug use (e.g. drug use in public, use of crack, and use of other drugs). A much clearer distinction can be made between the "care" group and the "treatment and care" group. Treatment and care agencies can thus better match their services to their clients or patients.