In writing, translating and adapting this Dictionary in 10. Edition, we took into account the extension of the light field of psychology in recent years and the many changes in this science, which have greatly increased the flow of it concepts considered. With this, the dictionary reaches nearly 10,000 voices. It has started from the principle that the client hopes to find more than one initial and generic. Accordingly topics are covered in detail. Many of the items correspond to sectors which are currently the subject of particular attention, such as biology, linguistics, cybernetics, information theory, the theory of systems, data processing and modern diagnostic techniques. We have tried to present the issues in ways that are understandable to everyone. The appendix devoted to the tests contains nearly 800, sorted by author. We included all study procedures in the teaching of psychology and applied in practice. Includes a very comprehensive test authors and Spanish language editions, adaptations and original Scale of foreigners. Do not omit the new concepts that have emerged in the field of psychological statistics. Within a few items are essential mathematical methods in the theory and practice of psychology. The references are more than 3,500 provided the Spanish translation, if any.