Most men who have sex with men (MSM) do not receive gonorrhea testing, contributing to delayed treatment and potentially amplifying antimicrobial resistance. Poor test uptake is often related to costs associated with STD testing and minimal community engagement. We have developed a pay-it-forward intervention to enhance gonorrhea testing among MSM. Pay-it-forward involves an individual receiving a gift (in this case, a gonorrhea test) and then be provided the opportunity to give a gift (in this case, money to support gonorrhea testing) to another person. Pay-it-forward is an example of upstream reciprocity theory suggesting that people who are helped by someone feel a “warm glow” that makes them more likely to help others. Pay-it-forward has been used to encourage people to donate something to another person. But in this study, we will test the effectiveness of two levels of implementation strategies based on upstream reciprocity to motivate gift recipients to get tested for gonorrhea. Specifically, we will compare a standard pay-it-forward implementation strategy with minimal encouragement to get tested and a community-engaged pay-it-forward strategy alongside a control arm in which men pay for their own STD test. Our pilot randomized controlled trial in two cities found that pay-it-forward substantially increased gonorrhea testing compared to the control arm (56% in the pay-it-forward arm, 18% in control arm). Our pilot data also suggests that greater MSM community engagement (e.g., MSM participatory activities to create testing messages) increases donations to the program, reinforcing the hypothesis that a community-engaged implementation strategy can activate upstream reciprocity. Intensified testing could also decrease antibiotic resistance. Building on our UNC Project-China research infrastructure in China, we propose the Pay-It-forward gONorrhEa tEsting RCT (PIONEER). The study has the following specific aims: (1) to use a three-arm cluster randomized controlled trial to compare gonorrhea testing uptake in a standard pay-it-forward strategy arm, a community-engaged pay-it-forward strategy arm, and a control arm reflecting current practice; (2) to determine mechanisms through which different pay-it-forward strategies activate upstream reciprocity to influence gonorrhea testing and donations; (3) to examine the impact of enhanced gonorrhea testing on the development of gonorrhea resistance. Based on our prior work, we hypothesize that a community-engaged pay-it-forward strategy will increase gonorrhea test uptake rates compared to the standard strategy, and that pay-it-forward in general is superior to the current practice of paid testing. Our proposal is innovative because it provides a new financing mechanism to support gonorrhea testing, tests implementation strategies to enhance the effectiveness of this mechanism, and will provide more detailed information about the relationship between increasing testing and the development of antimicr...