Manuel Aires de Matos

Abstract
PurposeNon-profit organizations (NPO) contribute significantly to the welfare of citizens and communities. Engagement in volunteering is crucial for sustaining volunteer motivation and for the effective and efficient functioning of NPO, with significant implications for society at large. Yet, literature on volunteer engagement (VE) is limited to date. Grounded on service-dominant logic, self-congruity theory and self-determination theory, this study aims to understand what motivates VE and how it may evolve into a co-creation process valuable to NPO and its stakeholders.Design/methodology/approachBased on survey data collected from 450 volunteers, working with a diverse set of NPO, a comprehensive model of drivers and outcomes of VE was empirically tested using PLS-SEM, considering the mediating role of volunteers' congruence with the core values of the NPO.FindingsThe impact of volunteers' perceived autonomy, competence and relatedness on VE and its subsequent role in volunteers' loyalty and extra-role engagement behaviors (i.e. co-development, influencing and mobilizing behaviors) were validated. Moreover, the study validates value congruence as an internalizing mediating mechanism in the engagement process, a role that has been implied but not empirically tested.Originality/valueThe study contributes to the engagement and volunteering literature, which despite an unprecedented parallel have developed almost independently, with limited reference to one another. As the nomological network of VE is still underexplored, the study extends the engagement literature to the volunteering sector, validating the key (but underexplored) role of self-determination needs and value congruence in driving VE and value co-creation behaviors. The study further adds to engagement research while addressing other actors' engagement beyond the customer–brand dyad. While adopting a seldom explored marketing perspective of VE, this study provides NPO valuable insights on how to manage and engage volunteers.