Although entry into adolescence is clearly demarcated by the somatic changes of puberty, the termination of this developmental phase is not clearly defined. The author seeks to establish criteria for defining the end of adolescence by describing the psychological tasks facing the late adolescent: the continuation and resolution of the oedipal conflict, particularly the negative (i.e., love for the parent of the same sex), the resolution of conflict over infantile traumata, and the achievement of ego continuity and a relatively stable character. He suggests ways in which one can recognize clinically both the healthy and the psycho-pathological resolutions of these adolescent tasks.