Although emotional dependence has been considered to be directed towards friends, only assessment instruments for measuring emotional dependence towards a partner have been found. The study aims to create and validate the “Questionnaire of Emotional Dependence on Friends (CDEA)”. Three studies were conducted to develop and validate the questionnaire. The preliminary version was administered to a sample of 278 adolescents, together with measures of emotional dependence on partners. The final version was administered to a sample of 675 adolescents, together with measures of attachment, stress, anxiety and depression. The CDEA scale was finally composed of 12 items grouped into two correlated dimensions: Exclusivity and Excessive Focus. It has shown adequate convergence with other emotional dependence instruments and related constructs. The CDEA is a brief self-report, valid and easy-to-complete assessment instrument that allows us to evaluate emotional dependence on friends in an adolescent population.