Using a systems perspective, a conceptual model is developed that encompasses a broad class of systems whose fundamental purpose is the support of managerial actions and decision making. The term management support systems (MSS) is used to label this broad class. This model is based on an extensive review of the relevant literature and available research. The result provides an integrated systems model of the phenomena involved and points to gaps in the research that arise largely from the attempts to examine various classes of MSS as separate entities. The research presented here is based on the premise that there are fundamental core consistencies or similarities among various types of systems that have evolved in the past several decades to support decision making. It presents a conceptual, theoretical model drawn from findings about various types of support systems described in the literature such as decision support systems (DSS), executive information systems (EIS), knowledge management systems (KMS), and business intelligence (BI). Pragmatic insights are provided by the conceptual model and recommendations for future research are discussed.