Results show that admissions entering treatment for marijuana abuse are not a homogeneous group. Although there are some similarities, admissions that abused marijuana only or that abused other drugs secondarily to marijuana form a distinct group from admissions that had a different primary drug and abused marijuana secondarily. The proportion of all substance abuse treatment admissions reporting the abuse of marijuana increased from 26.8 percent in 1992 to 37.3 percent in 2008, suggesting that the widespread use of marijuana among the general population along with the increased proportion of treatment admissions is a public health concern that impacts the general community and the substance abuse treatment system. Findings suggest that intake and assessment workers need to be careful in posing queries to elicit a drug use history in order to ensure as much accuracy as possible because in facilities with multiple modalities and/or where the American Society for Addiction Medicine (ASAM) Patient Placement Criteria are used, the information may be central to ensuring that the client receives the appropriate level of care at the beginning of his/her treatment. 6 figures and 3 notes