PROJECT SUMMARY / ABSTRACT This is an application for a five-year K01 award for Dr. Lawrence Long, a Research Assistant Professor at Boston University. The K01 award will support a complementary set of training activities and research aims aimed at establishing Dr. Long as an independent researcher in the field of HIV prevention and behavioral economics. This will allow Dr. Long to reach his long-term career goal of leading HIV research that guides the design of health delivery programs (treatment and prevention) which encourages optimal health behavior and decision making. The K01 will provide the support necessary to accomplish the following training goals: 1) to obtain expert technical knowledge in the use of pre-exposure prophylaxis (PrEP) in men who have sex with men; 2) to learn, master and apply the theory of human decision making; 3) to become skilled in the design and implementation of behavior change interventions and 4) to successfully apply for independent research funding. In order to achieve these training goals Dr. Long has proposed a career development plan centered around strong mentorship supported by didactic training in behavioral economics, qualitative research methods, and research approaches for working with vulnerable populations. Despite the largest HIV treatment program in the world South Africa’s HIV incidence remains high, in particular amongst key populations such as men who have sex with men (MSM). The recent inclusion of HIV pre-exposure prophylaxis (PrEP) as part of the national prevention package in South Africa is considered key to reducing incidence in these populations, yet pilot studies show sub optimal uptake and poor persistence amongst those most at risk. Dr. Long’s research will focus on understanding why PrEP uptake and persistence amongst MSM in South Africa is low and how the delivery of PrEP to this population could be altered to encourage those most at risk to start treatment. The research will aim to: 1) identify predictors of PrEP initiation and persistence amongst South African MSM testing negative at PREP pilot sites; 2) qualitatively examine the role of cognitive bias in the decision to request, offer, accept and continue on PrEP from a health care provider and patient perspective; and 3) develop and pilot a simple intervention to increase the uptake of and persistence on PrEP in MSM using behavioral economic theory to improve decision making. In order to accomplish these aims Dr. Long has access to the two pilot sites currently offering PrEP to MSM in South Africa. Before the completion of the K01 award Dr. Long will use this research as the basis for an R01 grant application which would aim to conduct a randomized control trial to establish the effectiveness of behavioral economic interventions in improving PrEP uptake amongst various key populations.