This paper discusses the psychic issues of studiousness and laziness in children and adolescents from a psychoanalytical point of view. The “working child” is presented as one who is able to separate himself/herself from the motherly environment, to control his/her aggressiveness, to enjoy thinking, and to accept not to know all. These conditions are linked with infantile instinctual life and its vicissitudes. Laziness appears, on the contrary, as a depressive and transgressive expression of psychic functioning. In regard to adolescents, the author insists on the novelty that is « thinking and working for one's self », capacity that participates to the access to a new generational identity and subjectivation. The importance of laziness within the adolescent process, that is to say its contribution to a renewed elaboration of the depressive position, is also emphasized. Finally, the author considers “playing”, as elaborated by Winnicott, as the paradigm of an essential laziness, at all ages, because it leads to creativity and disalienation of thought.