Cross-substance distributions of initiation status (never, late, or early) for alcohol, cigarettes, and cannabis are shown in Table 1. Significant associations were found between initiation of alcohol and cigarettes (χ2(4) = 59.70; p < .001; r = 0.40), alcohol and cannabis (χ2(4) = 83.86; p < .001; r = 0.47), and cigarettes and cannabis (χ2(4) = 94.74; p < .001; r = 0.51). Patterns of cross-substance use initiation were in the expected direction, with those who had never used a given substance being the least likely to use other substances. Early users, by contrast, were the most likely to report co-occurring substance use, frequently reporting that they began using other substances at an early age as well. For example, 79.3% of women who had abstained from ever using alcohol never tried cannabis, whereas 46.0% of those who began drinking at 16 years of age or younger reported first using cannabis at or before age 16.
