PROJECT ABSTRACT Injectable hormonal contraception is an important part of the method mix globally, with depot medroxyprogesterone acetate (DMPA) the most commonly used injectable product. Many women find injectables more convenient and discreet than taking a daily birth control pill, and some prefer this method to device-based longer-acting reversible methods (e.g., intrauterine devices; implants). Although with ideal use DMPA is over 99% effective, several features have limited compliance and hence effectiveness, including barriers/inconvenience associated with returning to the clinic every three months, side effects/menstrual pattern changes, and long/unpredictable return to fertility. In fact, one- year continuation rates can be as low as 40%. Daré Bioscience is developing a long-acting injectable (LAI) that provides extended release of etonogestrel with precise control over drug release rate, targeting windows of protection for six months and 12 months, a rapid return of fertility within two months, a steadier hormone dose than currently available therapies, and anticipated side effects similar to Nexplanon® (the currently-approved method of delivering etonogestrel). End-user research is critical for designing an LAI that users will find acceptable, to increase the likelihood of future uptake and consistent use. This R43 study, conducted in partnership with the Population Council, comprises end- user research with US women to understand their preferences for LAI duration in light of other attributes (particularly effect on menstruation, side effects, and return to fertility), acceptability of the LAIs vs. other contraceptive methods, and heterogeneity in duration preferences and acceptability between different end-user profiles. We will leverage Amazon’s Mechanical Turk (MTurk) platform to efficiently survey a national sample of 1,000 women ages 18-44 years, stratified by age group, urban/rural residence, and ever-use of hormonal contraception. In Aim 1, we will examine women’s LAI duration preferences, considering other product attributes, by implementing a discrete choice experiment (DCE), as well as acceptability of the LAIs compared with currently available contraceptive methods. In Aim 2, we will identify distinct LAI end-user profiles via latent class analyses (LCA), and LAI duration preferences for each. LCA models will include end users’ overall perceived acceptability of the LAIs, socio-demographic characteristics, fertility intentions, reproductive history, and contraceptive history/general preferences. Findings from this study will directly inform which LAI duration(s) to pursue and identify the characteristics of US women most likely to be interested in using an LAI. If this R43 study is successful, as defined by confirmation of hypotheses that the LAI would fill unmet contraceptive needs, we will pursue an evaluation of end-user experiences using our selected LAI prototype(s) within the first in-human Phase I trial of an LAI.