Purpose: Enterprise Social Network (ESN) systems have emerged as the technology of choice to bolster and support organizational efforts for harnessing embedded knowledge. However, a lack of understanding about it limits the optimization of its potential. Hence, this paper aims to assess the role of hedonic motivation, network externalities (NE) and top management support in conjugation with the unified theory of acceptance and use of technology theory to understand ESN’s usage for knowledge sharing. Design/methodology/approach: Data were collected from 187 ESN users through a survey questionnaire and subsequently analyzed using variance-based structural equation modeling using the partial least squares method. Findings: ESNs are used both for utilitarian and hedonic purposes. Furthermore, the results also bring out the importance of externalities arising from an extensive network of users and complimentary services, as well as support regarding resources and recognition from the top management toward reinforcing the benefits of using ESNs. Research limitations/implications: This study advances earlier knowledge by assessing the actual usage of ESNs for knowledge sharing. It takes into consideration multiple input variables, namely, performance expectancy, effort expectancy, NE amongst others to best resonate with the key factors driving its adoption and usage by an individual. However, because of the cross-sectional research design, causality can only be inferred. Practical implications: The organizations are recommended to have in place the measures for attaining optimal usage of ESNs, and in turn, witness knowledge moves around in ways unfathomable. Steps should be taken to develop tools and ecosystems to provide users affordances for both increasing productivity, as well as opportunities for gaining pleasure. Originality/value: This study is one of its kind effort to synthesize the knowledge about the ESNs in an Indian context. It provides fascinating insights into the determinants of intention and usage of ESNs for knowledge sharing. © 2019, Emerald Publishing Limited.