Eating Disorders are very widespread within the adolescent population. A possible interpretation and the comprehension of such forms of psychopathology may revolve around the failure to develop a well-defined personal identity, an incapacity to achieve a sense of differentiation with respect to others, an incapacity to measure oneself against others, dependence on others, the fear of rejection and a sense of inadequacy. This study explores the relational styles and behaviour of individuals suffering from eating disorders and their influence on the development of the personality, with reference being made in particular to self-valuation, dependence on others and levels of differentiation. A sample population of 90 women with eating disorders was studied. The subjects were subdivided into 3 groups (30 with restricting anorexia nervosa, 30 with binge-eating/purging anorexia nervosa and 30 with bulimia nervosa), overlapping in terms of age, duration of disorders and interrelation style, using the Relational Competence Test. The most significant results of this study concern the question of the definition of an autonomous personal identity. This process seems to be in progress in young women suffering from bulimia nervosa who appear to be driven towards a "definition of the self in opposition" with the consequent tendency towards relational experiences outside their own family. In women with binge-eating/purging AN moreover an awareness of the difference between the self and others and of their state of dependence would appear to be present, however behaviour aimed at the determination of an autonomous self is not evident. In women with restricting anorexia nervosa a definition of the identity is totally absent; these women develop an omnipotent self in their 'oneness' with others. These relational aspects lead to the identification of a continuum between restricting anorexia nervosa, binge-eating/purging anorexia nervosa and bulimia nervosa in an evolutionary perspective regarding the self-with-others.