Abstract
This article (1) reviews the research to identify mechanisms that may underlie HIV heterosexual transmission in developed and developing countries, (2) examines linkages between sex and substance use HIV transmission risks, and (3) describes sex network measurement issues relevant to developing HIV preventive interventions. The research contributions of developed countries to understanding sexually transmitted HIV have long recognized the influence of substance use and sex networks. Research in developing countries has contributed significantly to the environmental and biological understanding of HIV sexual transmission dynamics. Although much of the research in developing countries has recruited participants from venues where alcohol or other substance use is pervasive (e.g., truck stops), few studies have explicitly examined the relationship between HIV sex risk and substance use in these contexts. Finally, sex network characteristics and structural features, which have been found to play identifiable roles in the spread of HIV, are measurable at the individual level and can contribute substantively to the development and the evaluation of HIV-preventive interventions implemented at the network or community level.