Aligning information technology (IT) strategy with business strategy has been one of the top concerns of practitioners and scholars for decades. Despite the documented positive effects of strategic alignment on organizational success, only a few organizations consider themselves in alignment. Although numerous studies exist about how to accomplish IT-business alignment, empirical studies based on strong theories have been rare in the literature. This study attempts to fulfill this gap by proposing and empirically validating a comprehensive strategic alignment model. Drawing on prior literature, we identified five antecedents of alignment; centralization, formalization, shared domain knowledge, successful IT history and relationship management. We further hypothesized that the effects of these antecedents are mediated by two drivers of alignment, which are conceptualized as the level of connection of IT and business planning and the level of communication between IT and business managers. Using survey data and structural equation modeling methodology, we show that both drivers had significant effects on alignment, and the effect of connection is about twice that of communications. Our findings also confirm the effects of all antecedents except centralization. Overall, the main contribution of this study is the development and empirical validation of a comprehensive strategic alignment model, providing a more ample prescriptive insight for managing IT-business strategic alignment.