The unrecognised potential of large N – Strengths and limitations of the German Microcensus exemplified by fertility research Due to a large number of cases (688.931 persons in 2012) the German Microcensus has a huge potential for analyses in demography and family sociology. Content is further improved by the new voluntary question on biological children of women. This paper aims to systematically assess the methodological background as well as limitations and potentials of the Microcensus using the example of fertility data. The analyses of nonresponse show that the way of questioning has a strong impact. The related bias could, however, be reduced by imputations. The main limitations are the cross-sectional design and missing data on the children of men and internal migration. The potential of the high case numbers of the Microcensus is systematically discussed by analyzing confidence intervals: It allows for in-dept differentiations for analyzing social structure, birth parities and time patterns. Finally, we discuss three research designs which are able to use this potential: Dendrogram analyses allow group differentiations for up to five levels and thus reveal detailed patterns of childlessness. Parity patterns by cohorts illustrate differences by occupational education. Third, the age-specific analyses of first births among several cohorts allow for identifying trends of recuperation which differ considerable between educational groups.