It is desirable that reasoning, problem-solving and decision-making skills should form an integral part of our private and professional lives. Here we show how these skills can be improved through the use of the ARDESOS program. To test the effect of the program, we have also developed an assessment test (PENCRISAL). Our results are going in the desired direction. The ability to decide and make inductive inferences was improved, and this improvement was also seen in argumentation, although indirectly. In the future we must therefore improve our interventions in all factors, but in particular those referring to induction and problem-solving. Much remains to be done from the procedural point of view, but the preliminary results are very promising and we are convinced that our initiative has a good conceptual grounding. (Contains 2 tables and 1 figure.)