"The history of coeducation in U.S. higher education is explored through an analysis of a database containing information on all institutions offering four-year undergraduate degrees that operated in 1897, 1924, 1934, or 1980, most of which still exist today. These data reveal surprises about...

"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...