The effectiveness of any system can only be measured in relation to its ability to support the user in the tasks they wish to carry out in those situations in which it has been designed to operate. Task analysis tools which break tasks down into component and measurable parts are used as a means of clarifying the support that a system should provide. This paper uses the practical example of work carried out in the agricultural sector to describe the potential of a specific approach to task analysis for the support of crop management decisions. The approach is based on the work of Arinze (1992), who proposes that the basic cognitive element of the decision task is a question, a user enquiry of the environment or system. This paper describes how his approach to the collation and organization of information was successfully used within the DESSAC project as a means of ensuring that the decision support system (DSS) adequately supported the decision task and more recently within the requirements phase of three smaller projects. The incorporation of the approach into a practical and flexible method for use within time and cost constrained DSS development projects is outlined.