It may seem unusual to begin a lecture by drawing the audience’s particular attention to its title. Very often the only function of the title which is chosen for a lecture is to indicate the general theme on, and around which, the lecturer will be speaking. In this present instance, however, I have chosen the title with particular care and thought. For it indicates clearly the central, and essential, point which I wish to make, namely that, although adolescence is a period of stress which produces problems both for the teenager and those adults who have a responsibility for his welfare and upbringing, it is an inevitable and necessary part of the normal process of growth, maturation and development.