Black gay men have less choice when it comes to sexual partners than other groups and, as a result, their sexual networks are closely knit. These tightly interconnected networks make the rapid spread of HIV more likely. In a study looking at social and sexual mixing between ethnic groups in men who have sex with men, H. Fisher Raymond and Willi McFarland, from the San Francisco Department of Public Health in the US, show that social barriers faced by Black gay men may have a serious impact on their health and well-being. Their findings are published in Springer's journal AIDS and Behavior.