Over their lifecourse, young adults develop different skills and preferences in relationship to the information sources they seek when having questions about health. Health information seeking behaviour (HISB) includes multiple, unequally accessed sources; yet most studies have focused on single sources and did not examine HISB's association with social inequalities. This study explores 'multiple-source' profiles and their association with socioeconomic characteristics. We analyzed cross-sectional data from the Interdisciplinary Study of Inequalities in Smoking involving 2093 young adults recruited in Montreal, Canada, in 2011-2012. We used latent class analysis to create profiles based on responses to questions regarding whether participants sought health professionals, family, friends or the Internet when having questions about health. Using multinomial logistic regression, we examined the associations between profiles and economic, social and cultural capital indicators: financial difficulties and transportation means, friend satisfaction and network size, and individual, mother's, and father's education. Five profiles were found: 'all sources' (42%), 'health professional centred' (29%), 'family only' (14%), 'Internet centred' (14%) and 'no sources' (2%). Participants with a larger social network and higher friend satisfaction were more likely to be in the 'all sources' group. Participants who experienced financial difficulties and completed college/university were less likely to be in the 'family only' group; those whose mother had completed college/university were more likely to be in this group. Our findings point to the importance of considering multiple sources to study HISB, especially when the capacity to seek multiple sources is unequally distributed. Scholars should acknowledge HISB's implications for health inequalities.