Systems development is replete with projects that represent substantial resource investments but result in systems that fail to meet users’ needs. Evidence-based development is an emerging idea intended to provide means for managing customer-vendor relationships and working systematically toward meeting customer needs. We are suggesting that the effects of the use of a system should play a prominent role in the contractual definition of IT projects and that contract fulfilment should be determined on the basis of evidence of these effects. Based on two ongoing studies of home-care management and electronic patient records for diabetes patients, this paper reports research in progress regarding the prospects and pitfalls of evidence-based development. Author Keywords Evidence-based development, effects, user-centred design ACM Classification Keywords