Prior studies on knowledge sharing have concentrated primarily on either organizational or individual characteristics. However, by focusing on the interaction between members in On-line communities of practice (CoPs), we seek to identify and analyze factors that affect knowledge sharing by members in CoPs. Therefore, we examine if the independent variables such as interactivity, followership, and trust have positive impacts on the dependent variables such as commitment to CoPs and intention to share knowledge. In addition, this study also investigates the relationship between commitment to CoP and intention to share knowledge. The empirical results show that interactivity has a positive impact on commitment, but an insignificant impact on intention to share knowledge. Besides, trust between members is significantly associated with intention to share knowledge, whereas it does not have a significant effect on commitment. Moreover, followership is significantly related to both commitment and intention to share knowledge. These empirical findings show that the relationship between members in CoPs play a significant, positive role in intention to share knowledge. In conclusion, this research contributes to shedding a light into both interactions between members in and commitment to CoPs that are critical to facilitate knowledge sharing.