(1) To design and pilot a mobile-phone-based high-frequency survey platform to measure sexual behavior and contraceptive use among young women. The app will be used to gather weekly data on sexual behavior and contraception use in a highly anonymized, private forum. By developing an appealing, user-friendly mobile app, we will both increase participant adherence and the accuracy of this sensitive data. We will also be able to gather data at a much higher frequency than is practical with in-person surveys, allowing the measurement of how contraception use varies across partners and encounters, which will reveal which barriers are materially important to use. (2) To launch this survey to 1,000 female undergraduates at the University of Zambia and collect weekly data for 12 months, beginning in fall 2018. This population is important and under-studied: they are women with a high demonstrated value of education, and thus high opportunity cost of pregnancy. Nonetheless, focus groups suggest barriers to contraception use still persist in this group, but little is known about the actual incidence of unintended pregnancy, or it’s consequences. This weekly survey, consisting of 5-10 questions about last sexual encounter, including method of contraceptive (for users), and barriers to usage (for non-users), pregnancy if it occurs, and subsequent outcomes, will allow us to generate high frequency data on women’s contraceptive choices and outcomes. We will recruit women in their dorms using female surveyors at the beginning of the term. Each week, women will be prompted by the application to fill out the survey, and their responses will be sent to the researchers on a secure server. (3) To analyze these data to better understand the extent to which pregnancy can be a barrier to tertiary education among this population, and to document potential barriers to contraceptive use. The unique, high frequency data on sexual encounters, pregnancy, and contraceptive use across different encounters collected through the app will provide several new insights, providing evidence that could be used in the optimal design of policy and contraception-promoting interventions. Multiple observations across encounters and partners for a given woman will help disentangle the quantitative importance of different barriers to contraceptive use, including those that are woman-specific (which require access or informational interventions, partner-specific (and could be addressed by bargaining interventions, or example), or encounter-specific (which might be addressed by greater access to long-acting methods). The longitudinal nature of the data will allow us to document the incidence of pregnancy in this important population, as well as the frequency of unintended pregnancy. Moreover, we will use the fine timing of the data to document the extent to which pregnancy could be causing dropout, as well as other outcomes following pregnancy.