Prospective longitudinal data from over 14,000 youth residing in 28 communities in the rural United States were analyzed to examine the emergence of mixed-sex friendship groups in early adolescence. Youth were surveyed on 5 occasions between fall of 6th grade and spring of 9th grade. At each assessment, youth reported the names of up to 7…

This study focuses on the sexual phenomenon of "hooking up." A hook-up is defined as a single sexual encounter that may or may not include sexual intercourse with someone who is a stranger, brief acquaintance, or friend. The aim of this study was to document the prevalence of hook-ups in a sample of 1,011 urban middle and high school…

This article compares prevalence estimates of substance use and delinquent behavior in Washington State, United States and Victoria, Australia, two states chosen for their different policy environments around problem behavior. Few comparisons of international differences on rates of multiple problem behavior exist, and most are based on methods…