The perspectives of modern society's development depend largely on education and self- development related activity in the younger generation. However, the subjective and activity-related determinants of this type of activity have not yet been thoroughly studied. The purpose of this study is to identify subjective and activity-related characteristics which determine students’ educational and developmental activity. The study was conducted on a sample of 229 students aged 15-25 years old, in general, secondary, vocational and higher education. It used four established instruments. K.M. Sheldon's Self-Determination Scale modified by E.N. Osin, E.N. Volkova's and I.A. Seregina's Questionnaire for studying subjectivity structure, M.A. Shchukina's “Personal subjectivity development level” technique, and E.Yu. Mandrikova's Activity self-organization questionnaire. A further questionnaire was developed by the author, to determine the level of manifestation of personal educational and developmental activity and its relation to the characteristics which are performed to implement the activity. It was found that young people who exhibit a high level of educational and developmental activity demonstrate subjectivity, conscious activity, freedom of choice and personal responsibility to a greater degree, when it comes to their behaviour strategies. These individuals have better developed skills for organizing their activities, which are conditioned by purposefulness, and other characteristics related to implementing this type of activity. It has been shown that depending on age, the correlation between subjective and activity-related characteristics changes. Some of the characteristics grow and stabilize, while others regress and change. This is especially visible in subjective factors. It has been discovered that predictors of students’ educational and developmental activity are the characteristics related to that activity; the impact of subjective factors is minimal. These conclusions are supported by statistical analysis of data. The study materials can be applied nature and used for organization of young people's educational and developmental activity taking into account their age-related peculiarities.