This special issue is dedicated to the 3rd Estoril Vigotsky Conference-the biannual international scientific event held in Estoril, Portugal on 16-18 June 2014. The organizing committee honored the wide impact of Lev Vygotsky's works on contemporary psychology and included Vigotskyan League of Portuguese Language and the Institute Quintino Aires, in collaboration with the Lomonosov Moscow State University, the Russian University of Humanities (Russia, Moscow), IPAF-Instituto Vigotsky (São Paulo, Brazil) and Andricard (Luanda, Angola). The editorial board of our journal is very grateful to Professor Quintino-Aires for organization of this outstanding conference and to Professor Margarida César for contribution to this special issue. L.S. Vygotsky founded the socio-cultural approach to understanding cognitive processes in child development and introduced the genetic (developmental) method for their study. He also introduced the concept of cultural tools or mediational means, in his belief the higher mental functions to be products of social processes. The Theory and methodology section starts with an article by Andrei I. Podolskiy that discusses the practical implementation of another outstanding theory within the cultural-historical approach-by P.Ya. Galperin. The article's title There's nothing so practical as a good theory could be the motto of this special issue, because it includes classic theoretical papers as well as applied research and empirical data from professional practice. From the standpoints of the intersubjectivity concept, Anatoly N. Krichevets explores Lev Vygotsky's quintessential statement that "Every function in the child's cultural development appears twice: on the social and on the individual levels-first between people (interpsychological) and then within the child (intrapsychological)". Pedro Ferreira Alves joins developmental psychologists and cognitive scientists around the world in discussion of L.S. Vygotsky and J. Piaget's dialogue on formation of scientific concepts. The idea of external mediation in rehabilitation of mental functioning became the basis of major neuropsychological developments, including the works by A.R. Luria. The largest section of the issue is dedicated to current questions of neuropsychology and clinical psychology.
