The main purpose of this study was to evaluate the effects of a package of activities, known as "Portfolio", on cognitive functioning, self-regulation, and academic achievement. The study was carried out with a group of 40 students from Compulsory Secondary Education (mean age 13 years old) during 120 hours distributed over two school years. A quasi-experimental pretest-posttest-1 and posttest-2 design was employed. Treatment consisted of the administration of specifically selected tasks, assessed in previous studies, from the psycho-pedagogical Instrumental Enrichment Program, the Philosophy for Children Program, and Project Intelligence. The students were evaluated in the criteria variables at the beginning and at the end of treatment, and once again two years later. The results indicate that the procedure was effective in all the variables studied and that the gains observed at posttest-1 were maintained for at least two years after the intervention. Some relevant conclusions and suggestions at the educational and scientific level are commented upon. (Contains 3 tables.)