Abstract: Flexibility, variously known as adaptability, tailorability, and customizability, has long been recognized as important in information system (IS) success. Reliability has known value in IS for the resulting predictability it bestows on a system. However increasing flexibility can increase possible paths for system breakdown, and so contribute to failure, i.e. increasing flexibility can reduce reliability. Reliability and flexibility seem in design “tension”, as one creates change and the other resists it. The combination of reliability and flexibility has been called “ robustness”, and it seems a desirable integration particularly for emergency response systems. However typically these two areas are studied separately. Our approach to evaluating the combination of reliability and flexibility is to define two distinct requirements that neither overlap nor contradict, and can be assessed by system users. A questionnaire instrument for users is proposed for measurement of the flexibility and reliability of a system. © Proceedings ISCRAM 2004.