The author deals with the question of a general assessment of difficulty in foreign language texts designed for reading practice with the aim of classifying them from the easiest to the most difficult. In doing so we must take into consideration the length of the text and its difficulty as regards vocabulary, grammar, style and idiomatic expressions. The assessment carried out according to individual viewpoints can be expressed in simple indices of difficulty and the overall assessment according to a number of different viewpoints can be expressed by a synthetic index, which equals to the geometrical average of the appropriate simple indices. The author uses eight selected short English texts to illustrate the practical use of simple and synthetic indices resulting from an a priori didactic-linguistic assessment of their difficulty. Then he confronts the result of this a priori assessment with the result of the experiment: pupils at two secondary schools, where English is taught, were set the task of translating the eight above-mentioned texts and the points to be assessed were the correctness of the translation, the time necessary for a correct translation of each of the texts, and the number of words the pupils had to look up in the dictionary. The correlation g between the degree of difficulty of the texts determined on the basis of an a priori didactic-linguistic assessment and the degree of difficulty of the same texts determined on the basis of an experiment amounts to 0.79. Thus it seems an a priori assessment of the difficulty of texts carried out according to the abovementioned method may to a great extent replace the empirical assessment, or at least make it more accurate.