A long-term research into the level of the reading skills of pupils when passing from the 5th to the 6th-year class of the Nine-Year School, carried out in the South Bohemian Region, has shown that the reading skills of a ≪relatively great pro- portion of pupils do not correspond to their psychological capacities. This disproportion was especially marked in the case of bad readers. In order to find out the possibilities of timely remedy, an experiment was carried out at three schools in a border district of the South Bohemian Region. The experiment was carried out in the 4th and 6th-year classes in the 1968/69 school year, and its aim was to show the possibilities of a differentiated and individual approach to the pupil on the basis of a better psychological knowledge of the pupil’s personality. The registration of the reading performances at the beginning of the 1968/69 school year, statistical processing of the quantifiable components of the reading skill and the psychological examination of the capacities of the pupils, provided the necessary data for judging the level of the reading skill of individual pupils in relation to their psychological capacities, and made it possible in the 4th-year classes to outline a prognosis of each pupil’s further development. For experimental reasons the criteria of assessment worked out for the 6th-year class were applied to the 4th-year Glass as well. A repeated registration of the reading performances at the end of the school year in June 1969 showed that the 4th-year pupils’ performances very much approached the performances of the 6th-year pupils at the beginning of the school year in all the basic components of the reading skill (speed, remaining deformations, and defects in intonation). The experiment has thus shown, that the general average level of the reading skill attained by the end of the fifth year can be achieved a whole year earlier. An alternative psychological prognosis (going to improve, not going to improve) concerning backward readers, pronounced at the beginning of the 1968/69 school year, has proved to be 93.75 per cent correct. The dynamics of developing the reading skill in the experimental 4th-year classes has also indicated the perspectives of suitably applying differentiation and individualization of the teaching process on the scientific basis of psychology.