Leaving school has far reaching consequences both for the individual and the society. We tackled this problem by using Bronfenbrenner's ecological systems theory to analyse case studies of 12 children (elementary and secondary schools) who quit schooling or are under risk to do so. It is an adequate frame of reference for understanding the causes of school-leaving since it considers different levels of development and their relations. The children and four parents took part in semi-structured interviews. Other data were gathered by interviewing the focus groups of school principals, school pedagogues and psychologists, teachers, Parent Councils, and pupils. The qualitative analysis shows a disturbed structure and functioning even at the level of microsystem (family, school, peers) which may be linked with school-leaving. The relations between microsystems are sporadic and inadequate (mesosystem) which additionally stimulates school-leaving. Higher levels of environment (exo and macro systems) in which children do not participate, yet depend upon their indirect influence, stimulate school leaving, too. Many children were faced with nonnormative life events (chrono-system: divorce or death of parent/s, underage pregnancy, family moving). We view this research as the initial step which will identify the problems and lead to future directions of research which would, based on Bronfenbrenner's approach, systematically examine different levels of environment and form the basis for creating ecologically valid measures for prevention of school-leaving.