A research in intelligence of students of Czechoslovak basic nine years school was made by Amthauer’s Test of intelligence structure (T-S-I) on a sample of 367 students of seventeen ninth grade classes — located in five different types of communities. The research was based on so called socio- psychical theory of intellectual abilities which, according to this point of view, are developing from a genetic code and inborne components by means of activity in socially conditioned environment. The way and weigh of this social influence was proved by results of research, which offer clear dependence of students’ intelligence profile on socio-cultural background of particular schools. This influence is mostly stimulative [in comparison of our results with the test norm) but partially causes retardation too. When analysed in more detail way it appears that socio-cultural background forms the structure of intelligence mainly and its influence is strongest in so called verbal ability of students. When measured on the scale rigidity — flexibility, the thinking of students gave also a show of some relation to their socio-cultural background. Besides higher rigidity found in less communities the rigidity of thinking rose in big cities too. The relation of test results and school grades was slightly more significant than usually. On the level of individuals however this comparison proves remarkable differences — caused by personal features of students and teachers as well.