Behaviors, emotions and cognitions form a triangle that is essential in the world of Psychology. Each corner of this triangle exerts a powerful influence on the other two, so for example, the way that we feel influences the way that we think about things and how we ultimately take decisions. This same triangle is present in child psychology, only it’s a bit more mysterious. So, what actually is child psychology? Child Psychology is a branch of Psychology that studies the changes in the previously mentioned triangle in the first eighteen years of the life of the individual. Considering that Child Psychology studies the progress of a person throughout some very specific life stages, it is naturally heavily associated with development psychology. Development psychology studies how the triangle evolves during the course of the individual’s whole life, nonetheless, it is traditionally and essentially associated to the life stages that antecede adulthood. Many of the topics in clinical psychology for adults also apply for children. Depression and anxiety disorders are the most common mental disorders for both of these life stages and their symptoms are exhibited in a similar way (although depression in children tends to be associated with irritation). Therefore, I will focus this article in a developmental perspective of child psychology.