Strategic management of Information Technology (IT) has long been regarded as a critical component of business performance. This study addresses two objectives. Firstly we investigate the practice and effectiveness of Strategic Information Systems Planning (SISP) as a function of strategic management in 29 large Australian organizations. Secondly we review these results through a theoretical lens established by Segars et al. (1998) who identified six dimensions that provide a structured approach to reviewing the SISP process. Our results show that SISP was widely used in these 29 organizations in aspects such as planning associated with strategic IS investment and application, and whilst the theoretical review generally supported the literature, some amendments are required to the participation and focus dimensions suggested by Segars et al. (1998). Such results have implications for both practitioners and researchers.