This article explores the characteristics of open and closed relationships in 170 gay men according to their levels of satisfaction, their attachment styles, and the rules of having sex outside their relationships for open couples. We found no significant difference between open or closed relationships in levels of satisfaction or attachment styles. However, we found that gay men in open relationships who have explicit rules about having sex with other men are significantly more satisfied that those gay men with no rules. A content analysis of the rules is presented and implications for therapy are drawn from the findings.