The objective of this protocol is to examine the utility of behavioral economics for understanding reinforcer interactions as they pertain to drug self-administration. In a series of 6 experiments, the researchers will attempt to quantify the effects of qualitatively different reinforcers (money, cigarettes, alcohol, nicotine gum) and their interactions. This work represents a continuation of research by this investigator in the area of addiction and pharmacology.

Inclusion Criteria:

• Use of 20 or more cigarettes per day
• CO levels >15 ppm
• More than 12 alcohol drinks per week and beer as preferred alcoholic beverage