This study evaluated a proposed classification system to assess the nature and extent of voice use in young singers to support diagnostic routines, the treatment of voice disorders, and future research in children and adolescents. A classification system was developed and studied in 186 children and adolescents (age range 6-19 years, M=13.5 years). The system was based on three parameters previously shown to contribute to the development of voice disorders in young singers: amount of voice strain, amount of voice training, and the amount of wind instrument use. The subjects were selected on the basis of information from schools and choirs. After this selection, they were interviewed in detail by seven phoniatricians, logopaedists, and voice teachers. The standardized interviews were recorded and used for classification. Afterward, 124 physicians/logopaedists, choirmasters, music teachers, and lay people classified the singing activity by means of six randomized interviews, resulting in a total of 744 second appraisals. The agreement concerning the classification on the part of the interviewers was evaluated for each preselection and each second appraisal result for all three dimensions of the classification for each subject. All of the second appraiser groups showed moderately strong agreement with the interviewers (kappa=0.65-0.83). In the selection in which the test subjects were not interviewed, there was significantly less agreement (kappa=0.29-0.47). However, the additional strain caused by the instrument was already appraised with a very high degree of agreement in the preliminary selection (kappa=0.88-0.93). This classification system is a practical instrument for evaluating singing activity in young singers. It is accessible to lay persons, simplifying and standardizing communication among physicians, logopaedists, and singing teachers. It can be used at the level of a group comparison in scientific investigations.