Within the last decades survival rates of pediatric CNS-tumor patients were constantly rising due to better treatment options. Therefore, late effects have become a paramount issue. Survivors are especially at high risk for developing functional deficits. Consequently, restrictions in participation in everyday life may occur. Besides illness- and treatmentspecific aspects, especially early school (re-)integration turned out to be a good predictor of a high participation level. However, as we know from outcome studies of the past years, in many cases survival was the only outcome indicator. Whenever cognition was included in these investigations, single outcome measures like the IQ were used, which are useless regarding a detailed description of strengths and deficits. Only in the past years, more appropriately, neurocognitive functions like attention, memory or executive functions were included in the studies. However, often a discrepancy between the scores on psychological tests and observations of patients, parents and teachers in everyday life occurred, which led to misunderstandings in terms of rehabilitative interventions. Therefore, the present thesis aims at filling the information gap between neurocognitive test results and individual perceptions of the patients possibilities to participate. In order to investigate those functional deficits that lead to participation restrictions in everyday life, the “Participation Scales 24/7” were developed. This set of questionnaires is supposed to collect data from different perspectives and, thereby, includes the views of students, parents and teachers on the individual participation possibilities of a chronically ill child. The WHO-International Classification of Functioning, Disability and Health offered the framework for the construction of single items of the questionnaires. ^After the development of the Participation Scales, altogether 1022 children were included in this study. 134 CNS-tumor patients were compared to a group of 45 non-CNS cancer patients, 258 patients with different chronic conditions as well as 585 healthy controls. For sampling, a multi-center-approach was used, including different hospitals in Austria and Germany. The test-theoretical analyses revealed that the questionnaires are a reliable and valid tool for investigating school participation. According to the results, CNS-tumor patients are at a very high risk for developing participation restrictions in the course of the illness. Illness- and treatment-related factors, e.g. the neurological or endocrinological condition of the patients, do influence functioning and participation to a large extent. These restrictions can easily be detected by the instrument developed in this study. The benefit of the Participation Scales is the possibility to directly target the subsequent interventions to these participation restrictions. Moreover, by using this instrument, not only deficits but also strengths, which may be used for compensation, can easily be identified. By including different perspectives (patients, parents and teachers), additional valuable information can be used for planning neuropsychosocial treatment. Furthermore, the Participation Scales may be used as an endpoint in CNS-tumor therapy optimizing trials, whenever survival rates of two different treatments can be regarded as equal. Then, fewer functional deficits and a higher degree of participation may be the outcome.