"Hypothesis generation, evaluation and testing are crucial components of many everyday tasks. They are fundamental processes not only for experts, such as clinicians, who are responsible of generating possible hypothesis explaining a cluster of symptoms, prior to evaluate them and finally issue diagnosis. We are continuously asked to generate hypothesis about alternative causes (e.g., ""Why is my baby crying?""), and very likely the composition of this set – sometimes not generated but externally given – critically influence the chosen course of action (e.g., ""Shall I feed him? Is she sick?""). However, hypothesis generation, hypothesis evaluation and hypothesis testing have never been thoroughly analyzed as three building blocks of a same process. In particular, only little attention has been paid to how the initial set of alternative generated/given hypotheses, together with their judged probability, influences the hypothesis testing strategies, in terms of search for information and inquiring strategies. Analyzing this complex process from a developmental perspective will help us disentangling the knowledge and the cognitive components of the process. This insight, together with an attempt to design both a descriptive and a prescriptive model of the organic process from the hypothesis generation phase to the solution, will allow us to develop interventions, especially in education."