The aim of this paper is to contribute to the decision of how to perform evaluation depending on the evaluation context. Three general strategies of how to perform evaluation are identified: Goal-free evaluation, goal-based and criteria-based evaluation. Two general strategies of what to evaluate are identified: IT-system as such and IT-system in use. From the three “how-strategies” and the two “what-strategies” we derive a matrix consisting of six generic types of evaluation. Each one of the six types are categorised on a ideal typical level. For each type there is suggested evaluation process model.