More and more the boundaries of online and oine spaces are becoming fuzzy. Hybrid communities have emerged as socio-technical platforms capitalizing on this fuzzy border. O ey support the blend of computer-mediated communications with face-to-face interactions. O is intertwined nature of online-o, ine interactions in hybrid communities pose extra burdens on their members, especially newcomers. Newcomers in the hybrid communities are required to make decisions about in-person meetings with strangers with scarce knowledge and limited commitment to the group. In this work, we explore what in Y uences newcomers' o, ine participation in the context of Meetup. Following a set of theoretical frameworks, we have identified factors relevant to newcomers' decisions about their first o, ine event and we have examined the impact of each of those factors through statistical regression models. Our results show that factors contributing to reducing uncertainty and sense of inclusiveness play a key role in newcomers' decision making process about what events to a S end o, ine. Based on our findings, we provide design guidelines for community technology developers to be S er support newcomers in their decision to start participating o, ine in hybrid communities.