Promoting civic engagement could be a way of strengthening the social solidarity of China's urban population. The drastic socio-economic changes resulting from recent economic reform are likely to have a deleterious effect on social solidarity. Based on a survey conducted in 2010 in the Southern China city of Xiamen, this paper examines a specific form of civic engagement - citizen cooperation - to resolve community problems, and assesses its relationship with social capital. The study reveals that discrepancies in the level of civic engagement exist among urban residents and that inequality of social capital plays a significant role in these discrepancies. The findings suggest that such gaps could be addressed by increasing social capital, especially by expanding residents' personal community networks.