Taking the knowledge-based view of the firm as its starting point, and acknowledging that knowledge can lie outside the firm, this research extends our understanding of how the growing social media trend can contribute to open innovation. It focuses specifically on small and medium-sized enterprises (SMEs), which tend to be resource constrained and might benefit particularly from leveraging social media platforms. The authors bring forward the notion that people flock to social media because they are motivated by a desire for social interaction. Indeed, the findings suggest that SMEs that put effort into connecting customers on social media – which the authors refer to as having a ‘social strategy’ – are likely to reap both customers’ involvement in innovation on social media and new knowledge of value for innovation. Examining differences between social media platforms used primarily for personal purposes and those used primarily for professional purposes, the authors find that a social strategy is more effective in the first category than in the second. This probably reflects differences in the social identities that people adopt on these two types of social media platforms.