This article explores a case of mistrust in global health research and community engagement. It uses ethnographic material collected in 2014 and 2016 in Kenya, concerning community engagement by a HIV vaccine research group working with men who have sex with men and transgender women. In 2010, the research group was attacked by members of the wider community. Following the attack, the research group set up an engagement program to reduce mistrust and re-build relationships. Analysis focusing on mistrust shows the dynamics underlying the conflict: Norms around gender and sexuality, political support for LGBTIQ+ rights, and resources disparities were all at stake for those embroiled in the conflict, including researchers, study participants, religious leaders, and LGBTIQ+ activists in the region. Rather than a normative good with liberatory potential, community engagement in this paper is discussed as a relational tool with which mistrust was managed, highlighting the fragility of participation.