"I discuss economic approaches to the demand for harmfully addictive substances and estimate time-series demand functions for the period from 1975 through 2003. My estimates suggest that changes in price can explain a good deal of the observed changes in cigarette smoking, binge alcohol...

"We study social interactions in the risky behavior of best-friend pairs in the National Longitudinal Study of Adolescent Health (Add Health). Focusing on friends who had not yet initiated a particular behavior (sex, smoking, marijuana use, truancy) by the first wave of the survey, we estimate...