Description: Current reforms of the German educational system are focussing on evaluation, school development and competition between schools. Due to the recent change from an input-driven to an output-driven steering paradigm, differences between the individual schools are becoming more salient, and school choice is becoming more relevant. Theoretical models and empirical research on educational decisions suggest that choice criteria and choice processes should vary between different social strata. This paper focuses (1) on how parents choose a school within a given track (e.g. Realschule/Gymnasium), and (2) on whether differences in school choice criteria and differences in the rationalities of school choices can be found for families of different socioeconomic backgrounds. Methodology: 1500 parents from two German cities completed an extensive school choice questionnaire. Among various other items, the questionnaire assessed school choice criteria in a free factor/list approach. Using a hierarchical content analytic category system, the choice criteria were classified in eight main categories. Information about the actual school choice process was collected using 10 rating items. Choice criteria and choice process items are analyzed together in a two-step-cluster analysis. The resulting clusters are related to a measure of socioeconomic background (ISEI scores; Ganzeboom et al., 1992) and a measure of educational attainment (CASMIN classification; Brauns & Steinmann, 1999). Conclusions: Results from content analysis show that "distance to home" is an important choice criterion, especially for schools of the "Realschule"-track. For schools of the higher track "Gymnasium", other criterions such as "school profile" are more important. In comparison "school quality" is mentioned rarely as a relevant criterion. Two-step-cluster analysis of the choice criteria and the choice process items yields five forms of choice with different rationalities. While parents with lower socioeconomic background and lower educational attainment are overrepresented in less elaborated "bounded rational" forms of choice, better educated parents with higher incomes are more prominent in the more knowledgeable "rational choice" forms. The less elaborated forms of choice tend to "go with the flow", while the more knowledgeable choosers are more likely to decide against the majority school. The results are discussed in the context of research on school quality, school composition effects and educational inequality.