Internet-based surveys are commonly utilized as a cost-effective mechanism for data collection in social and health psychology research. Little is known about the differences between partnered gay men who participate alone compared to those with partners who also agree to participate. A sample of 260 partnered gay/bisexual men from New York City completed an online survey covering demographic characteristics, sexual behavior, substance use, and relationship satisfaction. Upon completion, they had the option to send the study link to their partner. In total, 104 (40 %) participants successfully recruited their partners, 90 (34.6 %) were unsuccessful, and 66 (25.4 %) declined the option to refer their partners. Men who did not refer their partners were significantly older, in relationships longer, and reported higher personal income. Participants who successfully recruited partners reported significantly higher relationship satisfaction. While generalizability is limited given the diversity of methodological factors that influence research participation, these data provide an initial insight into the effects on sample composition imposed by the implementation of dyadic (vs. unpaired) designs in online studies.