PROJECT ABSTRACT In the US, 18% of new HIV infections occur among cisgender women (cis-women), with these rates reaching as high as 30% in some parts of the U.S., however, only 7% of eligible cis-women have been prescribed pre- exposure prophylaxis (PrEP) for the prevention of HIV infection. Notably, areas with higher HIV incidence among cis women also have the lowest rates of PrEP uptake among this group. Unlike men who have sex with men or trans-women, cis-women are more likely to seek PrEP from a variety of clinical settings including ones that focus more on sexual and reproductive health and family planning, such as OB/GYN healthcare practices in addition to LGBT oriented services. There is a crucial need to develop the science of PrEP implementation in the context of sexual and reproductive health services for cis-women. Promising implementation strategies to improve PrEP delivery for women include targeting organizational/clinic factors, provider acceptability of PrEP as an HIV prevention strategy for cis-women, providers’ perceived scope of practice, and cis-women’s knowledge about specific considerations for PrEP. Audience segmentation is a novel approach that can assist in understanding this variability in implementation strategies, categorize sexual health providers based on their needs and organizational climates (audience segments), and to match these sub-populations to appropriate implementation strategies to increase the prescription of PrEP in order to curb HIV infection rates among at-risk cis-women. Utilizing a sequential mixed methods design and guided by the i-PARIHS framework, this study aims to develop implementation strategies that match the heterogenous needs of clinical providers in variable sexual health settings for increasing the uptake of PrEP among cis-women. Aim 1 will use qualitative methods (in-depth interviews sexual health providers working with cis-gender women who have prescriptive authority, PrEP eligible cis-women [cis-women on, and not currently on PrEP], and administrative stakeholders) to identify potential clinician characteristics and clinical environmental factors related to audience segments of sexual health providers. Qualitative findings will inform survey content to be used in Aim 2. Aim 2 includes quantitative surveys with ~340 sexual health providers, analyzed using latent class analysis to identify key audience segments based on providers’ patterns of responses, creating groups of individuals that have similar attitudes, needs, and organizational climates. Utilizing expert provider panels, Aim 3 seeks to match the audience segments to menus of implementation strategies suitable for the specific needs and organizational climates of these audience segments. The proposed study has the potential to make a significant contribution to our understanding of appropriate implementation strategies for the variable sexual health settings in which cis-women seek PrEP and the results of this study will provide...