Because the pathogens spread only within the unique context of a sexual union between people when one person is infectious, the other is susceptible to new infection, and condoms are not used to prevent transmission, epidemiological study of STIs is particularly challenging. Social network analysis entails the study of ties among people and how the structure and quality of such ties affects individuals and overall group dynamics. Although ascertaining complete sexual networks is difficult, application of this approach has provided unique insights into the spread of STIs that traditional individual-based epidemiologic methods do not capture. This paper provides a brief background of social network study design and assessments to illustrate how these methods have been applied to understanding the distribution of STIs to inform the development of interventions for STI control.