This article presents a multimethod, multi-informant comparison of community samples of committed gay male (n=30) and lesbian (n=30) couples with both committed (n=50 young engaged and n=40 older married) and noncommitted (n=109 exclusively dating) heterosexual pairs. Specifically, in this study the quality of same- and opposite-sex relationships was examined at multiple levels of analysis via self-reports and partner reports, laboratory observations, and measures of physiological reactivity during dyadic interactions. Additionally, individuals in same-sex, engaged, and marital relationships were compared with one another on adult attachment security as assessed through the coherence of participants' narratives about their childhood experiences. Results indicated that individuals in committed same-sex relationships were generally not distinguishable from their committed heterosexual counterparts, with one exception--lesbians were especially effective at working together harmoniously in laboratory observations.