For the past several years the Army Research Institute has been developing and testing SIMTOS—a simulated tactical operations system. SIMTOS may be described as a physical simulation of an Army command post in a controlled exercise environment. A major goal of SIMTOS is the examination of data handling by high level decision making personnel. In a typical SIMTOS experiment a group of senior military officers with tactical command experience are randomly divided into two groups, i.e., a standard and an experimental group. All Ss undergo two phases of simulated tactical operations—a planning phase and a combat phase. During each phase, mission criteria and subobjectives are imposed on the Ss. The two groups are evaluated in both phases of the experiment in regard to final scoring criteria based upon an ad hoc military school solution to the entire tactical exercise, and in respect to more immediate criteria (e.g., time to initiate action, number and types of information requests made to computer based data, etc.) related to the variable that defines the experimental group. To date the major research efforts associated with SIMTOS have been concerned with; (a) identification of minimum essential information requirements for offensive and defensive tactical operations planning; and, (b) evaluations of various methods of displaying information. The findings from these studies, coupled with information generated from a user workshop on displays and supported by field data, suggest that current Army requirements for tactical displays may be too stringent. That is, the display requirements may call for an excess amount of data with too great a level of detail. Tactical maps are a very good example of displays that may provide an excess of information. This presentation will describe the results of a study aimed at determining whether a set of tactical maps which are considerably reduced in detail can be used as effectively for tactical decision making as a set of standard Army tactical maps. Performance of the “standard map” and “reduced detail map” groups will be discussed in terms of general independent variables such as “tactical effectiveness” as well as task specific criteria such as; (a) area captured; (b) friendly troop attrition; (c) enemy attrition, etc. The implications of these results to other aspects of decision making and display research (e.g., management information systems) will be discussed.