The paper presents the course of development of Saint Petersburg Scientific School of Ontolinguistics (linguistic description of child language) developed in two in- stitutions: the Department of Grammar Theory of the Institute for Linguistic Studies in Russian Academy of Sciences and the Chair of Child Language of the Herzen Russian State Pedagogical University. The main ideas of this scientific school are analyzed to- gether with the achievements of its participants and the details of the principal projects concerning different aspects of L1 acquisition by children.