Introduction: The trouble with ‘Categories’: Rethinking men who have sex with men, transgender and their equivalents in HIV prevention and health promotion Richard Parker, Peter Aggleton, & Amaya G. Perez-Brumer 1. In the Name of Brevity: The Problem with Binary HIV Risk Categories Rachel Kaplan, Jae Sevelius, & Kira Ribeiro 2. The conflation of gender and sex: Gaps and opportunities in HIV data among transgender women and MSM Tonia Poteat, Danielle German, & Colin Flynn 3. Towards ‘reflexive epidemiology’: Conflation of cisgender male and transgender women sex workers and implications for global understandings of HIV prevalence Amaya G. Perez-Brumer, Catherine E. Oldenburg, Sari L. Reisner, Jesse L. Clark, & Richard G. Parker 4. A global research synthesis of HIV and STI biobehavioral risks in female-to-male (FTM) transgender adults Sari L. Reisner, & Gabriel R. Murchison 5. ‘Men who use the Internet to seek sex with men’: Rethinking sexuality in the transnational context of HIV prevention Rusty Souleymanov & Yu-Te Huang 6. From Marginal to Marginalised: The Inclusion of Men Who Have Sex with Men in Global and National AIDS Programs and Policy Tara McKay 7. From MSM to heteroflexibilities: Non-exclusive straight male identities and their implications for HIV prevention and health promotion Héctor Carrillo & Amanda Hoffman 8. What is in a label? Multiple meanings of ‘MSM’ among same-gender-loving Black men in Mississippi Nhan Truong, Amaya G. Perez-Brumer, Melissa Burton, June Gipson, & DeMarc Hickson 9. Switching on after nine: Black gay-identified men’s perceptions of sexual identities and partnerships in South African towns Joanne E. Mantell, Jack Tocco, Thomas Osmand, Theo Sandfort, & Tim Lane 10. Intersections and evolution of ‘Butch-trans’ categories in Puerto Rico: Needs and barriers of an invisible population Alíxida G. Ramos-Pibernus, Sheilla L. Rodríguez-Madera, Mark Padilla, Nelson Varas-Díaz,& Ricardo Vargas Molina 11. ‘You should build yourself up as a whole product’: Transgender female identity in Lima, Peru Lealah Pollock, Alfonso Silva-Santisteban, Jae Sevelius, & Ximena Salazar 12. HIV Vulnerability and the Erasure of Sexual and Gender Diversity in Abidjan, Côte d’Ivoire Matthew Thomann 13. Gender identity, healthcare access, and risk reduction among Malaysia’s mak nyah community Britton A. Gibson, Shan-Estelle Brown, Ronnye Rutledge, Jeffrey A. Wickersham, Adeeba Kamarulzaman, & Frederick L. Altice 14. The limitations of 'Black MSM' as a category: Why gender, sexuality, and desire still matter for social and biomedical HIV prevention methods Jonathan Garcia, Richard G. Parker, Caroline Parker, Patrick A. Wilson, Morgan Philbin, and Jennifer S. Hirsch 15. Sexual identities and sexual health within the Celtic nations: an exploratory study of men who have sex with men recruited through social media Kareena McAloney-Kocaman, Karen Lorimer, Paul Flowers, Mark Davis, Christina Knussen, & Jamie Frankis 16. "I am not a man": Trans-specific barriers and facilitators to PrEP acceptability among transgender women Jae M. Sevelius, JoAnne Keatley, Nikki Calma, & Emily Arnold 17. ‘Proyecto Orgullo’, an HIV prevention, empowerment and community mobilisation intervention for gay men and transgender women in Callao/Lima, Peru Andres Maiorana, Susan Kegeles, Ximena Salazar, Kelika Konda, Alfonso Silva-Santisteban, & Carlos Cáceres