The volume is composed by three different studies. First study: we investigate two key group determinants of participation in online communities, venue interactivity and community engagement, and consider their consequences on online and offline consumer behavior. Sets of hypotheses were theorized considering the differences between groups with different levels of interactivity and engagement. Many differences and key interactions emerge. Second study: find the factors that enhance member participation and sharing in business-to-customer virtual communities. We propose a causal model detailing the antecedents of different sharing behaviors. Managerial implications include free-riding-mitigating mechanisms employed in consumer communities to increase sharing behavior. Third study: we study the differences between firm and customer-managed brand communities. Results are derived using Netnographic, in-depth interviews and internet-based survey. We discuss the theoretical bases, the practical implications, and future research.