The article looks at two lines of Janet's investigations of personality - the involutionary and the evolutionary. The first was predominant in his early works and was linked to the problems of the subconscious, of a split personality, of psychological weakness, of the creative and conservative functions of the mind. The notion of self, according to P. Janet in that period, is a special judgement, the result of a combination of a certain number of psychological phenomena, that happens to be noted and understood. Later P. Janet increasingly focused on genetic analysis of personality formation, stages and mechanisms of development, possible difficulties in the process. Understanding personality as "work aimed at constructing integrity and differentiality", P. Janet emphasized the importance of interacting with other people in the process. A person's self is constructed on the analogy with another, and the other is "constructed" on the basis of one's own self.