Although blog service providers have developed and promoted various interactive functions of their blog platforms, effects of the interactivities on posting behaviour are still vague. Based on past literature, we proposed an information sharing behaviour model involving three types of interactivities, flow and satisfaction. A survey of 586 blog owners demonstrated strong support for the model. The results indicated that flow and satisfaction were positively affected by various types of interactivities and influenced the information sharing behaviour. Furthermore, gender differences in the relationships among interactivities, flow and satisfaction were found. Finally, the implications of this research were discussed.