The aim of this study is to collect longitudinal data on a starting sample of 4-year-olds in Kindergarten. Comprehensive theory-based surveys are carried out on children (as target persons), their parents, and educators, as well as heads of the Kindergartens attended, and, later on, the class teachers and elementary school principals. This data enables us to describe and analyze educational processes, educational trajectories, and the development of competencies.

Key research questions of this study refer to:

• competence development and educational trajectories in this age group,

• the learning environment of Kindergartens, elementary schools, and families, as well as learning opportunities in nonformal and informal settings,

• the transition from Kindergarten to elementary school and the associated educational decisions,

• the extent and the importance of social and ethnic disparities in Kindergartens and elementary schools and

• early returns to education.