Firms increasingly implement internal crowdsourcing to access the creative inputs of their wider crowd of distributed employees. Although internal crowdsourcing initiatives have attracted increasing attention from research, there is still a limited understanding about employee participation in these platforms. Previous studies have mainly focused on the participation of employees as innovators, disregarding other forms of employee participation occurring in these interactive platforms. Building on the literatures on employee-driven innovation and motivation, the main goal of this study is to investigate the behaviours performed by employees to support and refine others' ideas and their underlying motivations to do so, thus going beyond the role of innovators. Based on data collected from an internal crowdsourcing platform of a large European organization, we combine cluster analysis, social network analysis, interpretative content analysis and qualitative interviews to explore the content of employees' supporting behaviours in these initiatives and their underlying motivations. Overall, by looking at what employees contribute in these initiatives and why, this study contributes to generate a more comprehensive understanding of how internal crowds can be leveraged not only for idea generation but also for the support and refinement of others' ideas. Implications for innovation management research and practice are discussed.