This paper investigates online knowledge sharing behaviour in Baidu Knows, a platform sponsored by
the largest search engine company Baidu in China. We developed a spider engine to collect data from
over 2 million questions posted at Baidu Knows. The data collected allows us to profile registered
members, to answer questions such as who are the main driving force of those online communities and
their attributes, and who are the free-riders seldom posting and answering questions. We also test several
hypotheses in explaining the motivations of knowledge sharing, and the quality of such knowledge
sharing. Our results indicate that there is a large proportion of users who seldom answer questions, but
always ask questions. Although their behaviour seems selfish at the surface, they are actually the key
factors driving the growth of online knowledge sharing communitie