The growing popularity of micro-blogs has drawn an increasing amount of attention from users keen to expand friendship, facilitate information sharing and information seeking. Given the extensive use of micro-blog services, there is a pressing need to understand users’ behavioral intentions in micro-blog services. Although there are some studies exploring the factors explaining micro-blog users’ acceptance, none of research has been reported from both of the technological characteristics and network effects of micro-blog services. This study extended motivational model with socio-technical approach as a theoretical framework to examine the roles of technological factors and network effect factors in determining micro-blog users’ behavioral intentions. This study suggests that interactivity, convenience, accessibility, network size, existing social contacts, performance expectancy, sense of belonging and hedonic expectancy together provide a strong explanation for micro-blog use intention. The results of this study provide directions for system administrators and service providers to achieve higher levels of micro-blog usage by developing multi-faceted strategies.