This paper looks at the progress that the Mosaic database has enabled in the study of family structures in continental Europe in the past. Our main argument is that the combination of comprehensive archival research, digitization and computation, data mining, and open-access dissemination that is at the core of the Mosaic project is bringing about an important shift in the fundamental principles that have driven European family history research to date. These transformative features of Mosaic go beyond mere data infrastructural developments, as scaling up to much larger datasets leads to qualitative differences in measurements, methods, and questions. Integrating these perspectives can lead to an important incremental shift in both the scale and the scope of knowledge about historical European family systems.