The birth rate reducing to the level that does not ensure even the simple reproduction of the population, which leads to problems in the economy and social sphere and to migration crises, is a challenge for many developed countries. The demographic and family policy measures aim at solving this problem, which is reflected, for instance, in the Russian National Security Strategy approved on July 2, 2021 by the Decree of the President: the increasing birth rate is declared a required condition for increasing the country’s population. In contemporary Russia, the age model of fertility has transformed: the spreading practice of postponing childbirth in the last fifteen years has led to an increase in the modal age of mothers by more than five years, which is a factor in the decline in fertility. One of the mechanisms that can change this trend but lacks the due attention is the institution of the student family. The study aims at identifying those factors that determine the marriage intentions of the student youth. The article is based on the quantitative analysis of the surveys data of the Rosstat and authors’ sociological research, including logistic models and the decision tree method, which allowed to conduct modeling and select factors to identify the determinants of student marriage. The modeling results revealed the role of the value-system structure of students and their parental family in the motivation for marriage and starting family life. One of the main conclusions of practical significance is the confirmed importance for the youth of marriage as such and as a key stage in the life path, which under the postponing childbirth and reducing birth rate determines the need for the state support for the student family. The results of the study can help to solve a complex demographic problem of the decline and aging of the birth rate, which requires systematic work to create an image of the happy student family and to introduce mechanisms for supporting it.