Understanding the etiology of developmental brain disorders such as schizophrenia is critical for achieving advances in treatment and requires new research strategies that control for individual variation in genetic background, environmental challenges, and expression of phenotype. SYSGENET, a European systems genetics network for the study of complex genetic human diseases with mouse genetic reference populations, brought together in Helsinki a cross-disciplinary group of clinical and basic scientists and mouse geneticists to debate, formulate, and prioritize a strategy for future research based on mouse models. The main conclusions of this meeting are summarized here.