The development of psychologically healthy means for coping with sexuality is particularly difficult for disturbed adolescents who need residential treatment. One of the clearly definable psychodynamic constellations that underlie sexual acting out—an abortive mourning process in response to separations or losses suffered by female adolescent inpatients—is discussed. John Bowlby's theory of the mourning process is emphasized in understanding the immediate reaction to loss. Case material is presented in support of the hypothesis that in some disturbed female adolescents heterosexual acting out wards off a regressive wish, kindled by object loss, to reunite symbiotically with the preoedipal mother. Suggestions are given for milieu management and psychotherapy in such cases.