CM use was independently associated with injection drug use, and significant increases in injecting as the primary mode of administration were observed when patterns of use were considered longitudinally. Among 478 study participants, 339 (70.9 percent) had used CM previously. Of those who had used CM, the route of first administration included 11 who used oral ingestion (3.2 percent); 25 who injected (7.4 percent); 105 who snorted (31 percent); and 231 who smoked (68.1 percent). The proportion of respondents who reported current CM injection was significantly greater than the proportion who reported injection as the route for first CM use (18.3 percent compared with 7.4 percent). The ability to obtain CM the first time was reported as "very easy" or "easy" by 93.5 percent and 5.3 percent of participants, respectively. The 478 youth who participated in the study were enrolled in the At-Risk Youth Study prospective cohort. Extensive outreach produced a representative sample of Vancouver street youth who used illicit drugs. The study identified the circumstances of first CM use and factors linked with CM use among the cohort. 3 tables and 28 references