Previous studies linking online sexual partnerships to behavioral risks among men who have sex with men (MSM) may be subject to confounding and imprecise measurement of partnership-specific risks. We examined behavioral risks associated with having only online, only offline, or both online and offline partners in the past year, the confounding effects of multiple partnerships, and partnership-specific risks among a sample of MSM from New York City recruited offline in 2008. Overall, 28% of 479 participants had an online partner in the past year, but most of those (82%) also had an offline partner. Having an online partner was associated with past-year unprotected anal intercourse (UAI) and other risks, but not after controlling for multiple partnerships. There were slightly higher levels of risk within offline partnerships, but differences were largely attributable to MSM who had both offline and online partners. Last sex partners met offline were more likely to be HIV-serodiscordant and engage in concurrent substance use with the participant. This suggests that online partnerships may not be an independent cause of behavioral risks, but a marker for risks occurring independent of Internet use.