The authors extend the gateway theory by examining the relationship between the onset age of alcohol and the progression of drug use (alcohol, cigarettes, and marijuana) among 16 to 24 year old young adults residing in New York State. Logit analysis is employed to estimate the impact of the early onset of alcohol use on the subsequent use of other drugs. The findings suggest that alcohol use increases the chance of using cigarettes and marijuana, and alcohol-cigarette use significantly increases the likelihood of using marijuana. The early onset of alcohol use affects the current use of alcohol and other drugs; the impact is the strongest when the onset is initiated in a posited critical age period between 13 and 16.