Sex workers in Vancouver have been found to be highly vulnerable to a variety of negative health and safety outcomes, including high rates of occupational and historical violence, a high prevalence of HIV (approximately 25 percent within street-based sex workers in Vancouver), and limited access and use of health services. In order to mitigate some of the HIV and sexually transmitted infection (STI) risk in this population, researchers at the Gender and Sexual Health Initiative at the BC Centre for Excellence in HIV/AIDS are looking into understanding some of the larger structural and environmental determinants of HIV/STI risk. Dr. Kathleen Deering is studying a sample of sex workers in Metropolitan Vancouver to investigate the intersecting relationships between different social, environmental and structural factors, such as the availability and access to health services, neighbourhood of residence, and locations and venues of sex work. She will be measuring health and safety outcomes of these women (such as HIV/STI risks, including inconsistent condom use, number of sex partners and sex partnering patterns, and occupational and intimate partner violence) and the geographic distribution of these outcomes over time. This project will access data from a five-year longitudinal cohort of women in sex work in Vancouver, including 500 women and 250 youth sex workers who are 14 to 24 years of age. Participants will fill out a detailed survey and be asked to provide blood and urine samples for HIV and STI testing at the start and every six months for the five-year duration of the study. Dr. Deering will be using these data, combined with social epidemiology methods and Geographic Information Systems (GIS) mapping technology to help understand how social, structural and environmental factors impact risk patterns for HIV/STI and health services use and access. She will also be exploring the use of complex adaptive systems approaches as a novel and key methodological/analytical approach for examining multiple intersecting levels of risk. The results of this research will lead to important recommendations relating to changes in public health policy and the development of effective safer-environment interventions to improve the health and safety of women in sex work in Canadian settings. Results will be communicated to community members, the local and provincial government, and the study population through ongoing partnerships.