Strategic Information Systems Planning (SISP) has been widely researched, yet continues to be ranked as a key concern to IS managers. There have thus been calls for a strong theory to underpin SISP. In this study a theory is developed by integrating the findings from several major research studies published in the academic literature. The method employed is the grounded theory method, which is a qualitative research approach whose goal is specifically the generation of theory from data. The resultant theory possesses some unique characteristics as a result of using the grounded theory method.