The underlying assumptions and the structure of the enrollment analysis matrix (EAM) concept are discussed. EAM is a component of the Strategic Planning Project of the National Center for Higher Education Management Systems. EAM relates changes in the population of potential students external to the institution to the impacts that might result internally within the institution. Responses to upcoming changes can be studied by using the EAM to understand the differential changes that can be expected due to changes in an institution's environment. Examples of potential applications of EAM in postsecondary education planning and management are included, along with implementation guidelines and information on methods. Alternative applications of EAMs include: differential impact of demographic changes, costing, student-flow analysis, analysis of equity concerns, retention/attrition studies, curricular analysis, market segmentation for recruitment strategies, and student aid analysis. Included is a review of the literature on demographic changes affecting the college student populations in the 1980s and 1990s. Historical background on the EAM concept is also included, and some data elements and categories that might be included in EAMs are presented. Limitations and applicability of the EAM are identified, and basic report formats and possible software tools are discussed. A 44-item bibliography is appended. (SW)