In our study we aimed to define CNS-PNET subgroups. We performed Expression, Genotyping and/or Immunohistochemistry on 142 samples from 20 worldwide centers. Using these techniques, we have identified three molecular subgroups with distinct expression and copy number patterns, as well as, unique clinical characteristics. Specifically, these molecular subgroups were distinguished by primitive neural (group 1), oligoneural (group 2), and mesenchymal lineage (group 3) gene-expression signatures with differential expression of cell-lineage markers LIN28 and OLIG2. Our report underscores the importance of concerted, collaborative efforts to study large retrospective cohorts of tumours and patients to accelerate biological and ultimately therapeutic studies of rare tumours. The outcome of such a collaboration allowed us to identify LIN28 and OLIG2 as promising diagnostic and prognostic molecular markers for CNS PNET that warrant further assessment in prospective clinical trials.