This project entails a 3-phase mobile technology based and behavioral economics supported HIV prevention intervention - called Mobile Technology and Incentives (MOTIVES) - to increase engagement with HIV prevention information and improve testing frequency among Latino men who have sex with men (MSM) and transgender women (TGW). The study is conducted in collaboration with Bienestar Human Services, Inc. (Bienestar); a non-profit community-based service organization established in 1989 with sites located across Los Angeles County that primarily serves Latino populations. Specific Aim 1 included focus groups with MSM and TGW to finalize the planned intervention based on the insights from a preliminary study. Specific Aim 2 will enroll 200 HIV-negative MSM and TGW in a 12-month, two-arm randomized controlled trial (RCT). Those in the intervention group will receive weekly text messages with HIV prevention information and can win reward points for correctly answering weekly quizzes to keep them engaged and improve their retention of the HIV prevention information. Those who continue to test negative for HIV at least once every three months can enter a prize drawing to win prizes, with larger chances for those correctly answering the weekly quizzes. The control group will receive the same HIV prevention information but without the incentives. The secondary outcomes include sexual risk behaviors and HIV infection. Specific Aim 3 includes 6 exit focus groups (with 5-8 participants per group) to evaluate areas for study improvement and estimate parameters for future scale up. The Specific Aims are to 1) develop MOTIVES and finalize the weekly text message information content and the types of incentives; 2) implement and evaluate the impact of MOTIVES; and 3) evaluate areas of improvement for MOTIVES through focus groups and estimate mission-critical design parameters with point and confidence interval estimates for a subsequent, fully-powered R01 application.