Hybrid online-offline communities, known as online socio-technical platforms with explicit goals to facilitate offline interactions are thriving and more than ever obscuring the borders between physical and digital communities. However, members of these communities often face information asymmetry. Quality and information about the offline gatherings is visible to members who physically attend offline activities, but often not to those who did not attend the gatherings. Offline information such as the events’ whereabouts and the groups’ social dynamics can be essential to make the decision of attending a future event. In this dissertation, I studied the challenges and opportunities to utilize cross-boundary artifacts, defined as objects which capture offline activities and can be shared in the online space, to reduce information asymmetry in hybrid communities. I conducted three studies including an interview study with event organizers, an online survey, and a controlled lab experiment. The result of my interview reveals organizers most importantly judge the success of their event based on the offline experiences. They acknowledged the potential benefits of sharing offline experiences back to the online space (i.e. setting expectations, building community images), but also expressed concerns about the lack of support in current systems in representing offline interactions. The online survey and the controlled lab experiment then examined what roles cross-boundary artifacts can play in reducing information asymmetry and how they can be better incorporated and represented in the current systems. The results show that such artifacts embed rich and reliable signals and they convey valuable information about what happened in the offline activities. Their impact on offline participation varies by the format and volume of artifacts and the goals of target participants. My dissertation presents the first piece of research on hybrid communities focusing on the mechanisms and artifacts to connect online and offline spaces. This work also provides guidelines to designers, developers and practitioners of social technologies seeking to study or design technologies for hybrid communities
