The project will be undertaken in 3 counties of Kenya (Nairobi, Kisumu and Homa Bay) that have high HIV prevalence. 5 sites (2 government and 3 non-governmental) have been purposively selected for the demonstration because they serve high risk populations, have existing HIV prevention services and have adequate cohort of HIV negative clients who are potential candidates for PrEP. The sites include LVCT Health's Nairobi CBD and Tivoli sites, SWOP City clinic, Homa Bay County Referral Hospital and Korogocho Health Centre. The demonstration project will use a prospective cohort design employing mixed-methods. A cohort of 2100 PrEP users (female sex workers aged 18 and above, men who have sex with men aged 18 and above, young women at high HIV risk aged 15 -29) will be followed over 12 months to assess biological and behavioral outcomes through laboratory and survey assessments. This will be complemented by review of routine service delivery statistics (to assess PrEP uptake), cost data, and qualitative data to be obtained from in-depth interviews and focus groups with health providers, PrEP users, and peer educators/community health workers at multiple points in time.This project will be implemented in a 'real life' or 'real world' setting where there will be no control or comparison arms. However, pregnant women at enrolment and female participants who become pregnant during project implementation, who choose to continue on PrEP will be enrolled in a sub-group and followed through 12 months post-partum.