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 communities