Used data on 3,305 high school seniors collected as part of the 1984 Monitoring the Future project to examine the relationships among cigarette use, diet pill use, and use of amphetamines for weight loss. Results indicate that females were more likely than males to report use of all three substances. In addition, Whites were more likely than Blacks to use all three substances. Both female and male smokers were more likely than nonsmokers to use diet pills. Amphetamine use for weight loss was positively related to smoking among females, but not among males. The relationships between smoking and diet pill use, and smoking and amphetamine use to lose weight, were maintained when race, sex, and other drug use were controlled simultaneously. Two explanations for these relationships are considered. The first is that smoking is related to the use of most other licit and illicit drugs. The second explanation is that there is a greater preoccupation with weight among smokers, with weight concerns potentially motivating the initiation of smoking.