Prior research based on representative samples drawn from the general population suggests persons tend to follow a common developmental pathway from use of alcohol as youths through possible use of marijuana as teens potentially leading to use of more serious substances as adults. Based on this model, alcohol and marijuana act as gateways, whereby persons who do not onset to alcohol rarely onset to marijuana; similarly, non-marijuana users rarely onset to more serious substance use and abuse. This study examines whether a sample of serious drug abusers recruited from New York City in 1988-89 followed the same developmental pathway as observed in general populations. The results suggest that alcohol is not a prerequisite for progression to marijuana, but marijuana use nearly always precedes use of more serious substances such as cocaine, crack and heroin. Furthermore, with the growing prevalence of marijuana (since 1965) the importance of alcohol as a gateway to marijuana use appears to have declined and marijuana's role as a gateway to serious drug use appears to have increased.