Social commerce platforms have transformed industries, including tourism and hospitality. Online travel communities, equipped with social and commerce features, have shifted users from passive recipients to active value co-creators with tourism companies and other travellers. These communities enable users to exchange travel information, purchase products and services, and engage in meaningful social interactions. For tourism companies, these online travel communities rely on continuous user engagement in both community-activity participation and transactional participation. Despite the shift towards value co-creation, hospitality and tourism research still lacks a clear understanding of user participation in value co-creation activities within online travel communities, as well as the factors that motivate them to engage in these activities. Therefore, this research addresses this gap by examining how value co-creation is achieved in online travel communities. Specifically, this thesis develops a framework for the value co-creation mechanism and a scale to measure users’ motivations for value co-creation. Following a mixed-methods exploratory sequential design, this thesis consists of two studies. Study 1 employs a case study approach, integrating qualitative methods such as netnography and interviews (n = 32) to explore the value co-creation mechanism. Study 2 builds on these findings through a scale development study, conducted in two stages (Exploratory Factor Analysis & Confirmatory Factor Analysis) using online surveys (n = 426, n = 523) to refine and validate the measurement of users’ motivations for value co-creation. Findings reveal that online travel communities serve as platforms for users to interact and co-create value with other users, tourism companies and community employees. Value co-creation is facilitated by three key components: value co-creators’ engagement, resource integration activities, and interactions. Four motivations drive user participation: utilitarian motivation (economic benefits), social motivation (affiliation), personal integrative motivation (reputation), as well as personal and professional growth. This thesis advances research on value co-creation and motivation in the hospitality and tourism context by proposing a comprehensive value co-creation framework and a motivation scale for online travel communities. It also provides practical insights for tourism companies seeking to engage users and service providers in co-creating value.