How to achieve knowledge creation effectively remains a problem, this becomes even more difficult in a loosely knitted community such as networks of practice. This is because knowledge creation entails not only knowledge acquisition but also knowledge conversion. Both of them necessitate complicated social interactions. Since individuals are less likely to share precious insights with strangers, knowledge creation seems infeasible in networks of practice. To address this in a more comprehensive way, this study integrates social capital and TPB (theory of planned behavior) as well as individual motivations. The purpose of this paper is to delineate the relationships among salient antecedents of social capital and TPB, from which the factors that stimulate or impede individuals' knowledge creation can be specified. A survey instrument was used to collect data from a famous network of practice. 202 useful responses were employed to test our model. 11 of the 17 hypotheses are supported by the empirical findings. This paper also provides implications for both academics and practitioners. Key words: knowledge acquisition, knowledge conversion, networks of practice, TPB