Previous research has suggested that lesbian, gay, bisexual, and transgender (LGBT) individuals enter treatment for substance abuse with more severe problems than heterosexual individuals. However, methodological difficulties, particularly the difficulty of obtaining a representative sample, have limited the ability to draw conclusions about LGBT individuals who receive services for substance abuse. This study took advantage of a unique opportunity to examine a representative sample of openly LGBT clients receiving publicly funded substance abuse treatment by using data gathered by treatment providers in Washington State. Baseline differences between openly LGBT and heterosexual clients were compared in a variety of domains. Results demonstrated that openly LGBT clients enter treatment with more severe substance abuse problems, greater psychopathology, and greater medical service utilization when compared with heterosexual clients. When the analyses were stratified based on sex, different patterns of substance use and associated psychosocial characteristics emerged for the LGBT clients. Implications for provision of appropriate services and recommendations to treatment agencies are discussed in this article.