We examined the sequence of substance-use initiation in 375 street youth (age 13-21) who were interviewed from 1994-99 in Seattle, Washington. Based on the gateway theory, participants were categorized into six profiles to describe the order in which they initiated use of various substances (i.e., alcohol, marijuana, other drugs), or classified as nonprogressors if they had not tried all three classes of drugs. Youth progressing in the hypothesized gateway order (i.e., alcohol preceding marijuana, followed by other drugs) initiated their use at an earlier age than youth who had not progressed through all three substance classes. However, there was no relationship between a substance initiation profile and current substance-use. Implications include the recognition that street youth may follow different patterns of use than normative groups, and that interventions geared toward youth who use substances heavily must include contextual factors, in addition to substance-use history. (Authors)