Purpose – The purpose of this paper is to explore social media’s impact on organizational knowledge quality through the theoretical lens of social capital and resource exchange. Design/methodology/approach – This is a theory-confirming, quantitative study using panel data collected through a Web-based survey. Findings – The results show that while social media affects structural capital and cognitive capital directly, it only affects relational capital indirectly through structural and cognitive capital. Moreover, overall social media and the enhanced social capital do help promote organizational efforts in knowledge management, which subsequently leads to a higher level of organizational knowledge quality. Research limitations/implications – All survey respondents were from the USA, which may limit the generalizability of the findings. The authors also call for more research in establishing the time sequence in the proposed causal relations and in the individual-level mechanism through which social media promotes organizational knowledge quality. Practical implications – This study highlights both the potential and limitations of social media in promoting organizational knowledge management. Businesses must consciously manage the assimilation and use of social media to benefit from them. Originality/value – The authors position the study at the intersection of social media, social capital and knowledge management and explicate how social media work through social capital and organizational knowledge management efforts to affect knowledge quality.