Drug use, poverty, homelessness and sexually transmitted diseases (STDs) such as HIV are endemic in Vancouver’s Downtown Eastside. Melanie Rusch believes that improving the sexual health of marginalized populations is important for curbing the spread of STDs. She is studying a large sample of people who live in the Downtown Eastside to determine how behaviour patterns among these vulnerable populations affect sexual health. Her first aim is to study how different drugs and combinations of drugs affect sexual behaviours and STD rates. This includes estimating the impact of needle use, as opposed to sexual contact, on STD rates. Melanie’s second goal is to estimate STD rates of a group of women living in the Downtown Eastside. Melanie is investigating how their knowledge of STDs, exposure to outreach programs, and feelings of stigma affect use of health care services. Results of this research could be used to better define high-risk groups, identify barriers to accessing care, and tailor interventions to improve health of vulnerable populations.