The mutual relationship of sociology and pedagogy has many different sides and aspects. The scientific and technological revolution, which, since the middle of this century, has been going on in Czechoslovakia too, enriches this relationship with some specific attributes. In the first four chapters, having the character of communications, the author’s approach is informative: the question dealt with is that of the significance of sociology for the solution of methodological questions in pedagogical theory, for the elaboration of diagnostic methods in pedagogical practice, for long-term social planning of the development of society and for a scientific management of education. The fifth chapter is devoted to a detailed elaboration of the method of ascertaining and measuring the influence of social environment on the personality of the young person; it is based on the investigation of one of the most important development traits of the individual as a social personality, which is social maturity of man. The degree of social maturity reached by a person in his or her physical (chronological) age is ascertained by the quantification of the respective social phenomena and expressed by social quotient with the application of the statistical method to a great number °f cases under investigation. A continual (°pen) model of the personality, which the author creates in this way, corresponds to an empirically ascertained connection and probability dependences between social stimuli and individual responses (reactions) of persons under investigation. The function^ of social responses (competent performances, reactive potences) of the individuals tested are assessed, because of considerable age differences of the respondents, by the smallest squares method as symmetrically laid regressive straight line, whose equations make it possible to define the so-called social balance; by this is meant a situation in which the progressing and regressing aspects of the process of social maturing of a certain social age group or individual become balanced. The focal point of social balance thus arising is the geometrical picture of the quantitative measure of social maturity, which has been called social quotient. If the focal point of social maturity is formed by the point of intersection of the curved parts of symmetrically laid axial regressive curves, the author converts the non-linear dependence thus arisen into Richardson’s linear method. In order to express the social quotient SQR mathematically, the author proceeds from a definition laid down by E. A. Doll, in which SQ is expressed as a ratio of the Social Age SA and the Life Age LA ; but unlike Doll’s empirical and very complicated determination of a young person’s social age, the author, in examining the functional and intentional component of a young person’s social maturing process, defines the social age in an absolutely exact manner by an arithmetic average of pro- ducts consisting of standardized competent performances (reactive potences) SKS of the respective social group and social competences (reactive potences) tested SKT of any individual belonging to the social age group under consideration. (...) Thus the individual being tested and the social age group he or she belongs to, in the method described above consisting in the mutual study of their social maturity, form a unity both as regards ascertaining social competences concerning individual single social phenomena, and as regards the over-all social maturity of the young person’s personality. The value of the social quotient SQR obtained by the above method is an objective indicator of the influence of social environment on man’s personality and at the same time indicates his or her social profile, for it covers all the substantial aspects of the personality of socially maturing man. It is also an important criterion of comparison for ascertaining trends in the development of the youth and for foreseeing their behaviour in various situations. The social quotient can also be used for determining age ^flexibility and for predicting the development of the activity of the youth in a given society as a social age group of this society.