The author sums up the preliminary results of a research focussed on finding out the effectiveness of individual study of linear programmed instruction texts. The research was carried out at various vocational schools (age group 15—19), but especially at technical schools, involving altogether 535 students. The object of the research were two programmed instruction texts from the field of electrical engineering and electronics. The researchers were concerned with comparing the students’ knowledge acquired by the study of the subject-matter, which was presented once in the form of a linear programmed text and once in the conventional textbook form. A test given immediately after the study of the texts was finished showed that the students learning from programmed texts attained on an average approximately 6 per cent better results than those learning from the conventional texts. A test given one week later showed that the knowledge acquired by the study of programmed texts was more permanent than that acquired by the study of conventional texts. Students learning from programmed texts had forgotten approximately 5.8 per cent of the material, while those learning from the conventional texts had forgotten about 10 per cent of the material. It was further found that persons learning from the programmed texts needed on an average approximately 6 minutes longer for studying than those learning the same subject-matter from conventional texts.