Luxembourg’s student population is highly diverse in terms of language and family background and shows disparities in learning performances as early as first grade (Cycle 2.1). Achievement gaps might be increased by the high language demands in the traditional Luxembourgish school system. Early Childhood Education and Care (ECEC) including for instance crèche, précoce and Cycle 1, is one of the possible mechanisms to reduce these gaps that is currently discussed by researchers, policy makers, and the broad public. A lot of international literature points towards a positive association of ECEC and child development. However, findings vary widely with characteristics of ECEC, as well as characteristics of children and their families. For this report, we used data from the Luxembourg School Monitoring Programme “ÉpStan” from 2015 to 2021 including students’ learning performances in three domains in Cycle 2.1 – Luxembourgish listening comprehension, early literacy, mathematics – as well as student and parent questionnaire data. Additionally, data from ÉpStan 2022 on German and Luxembourgish listening comprehension and students’ language exposure at home are presented. Who attends which type of ECEC in Luxembourg? We find that the attendance in ECEC is generally high. On average, crèches were attended at a moderate level of intensity and duration. Family background (socioeconomic status, migration background and home language group) interacts in a complex way with attendance in ECEC. For example, children from families with a high socioeconomic status speaking Portuguese or French at home, attended crèche for more hours a week than children from families with a high socioeconomic status speaking Luxembourgish at home. In regard to language exposure in ECEC, Luxembourgish appears to play a dominant role for most children. How are ECEC attendance and family background associated with learning performance in Cycle 2.1? Most importantly, non-formal (crèche) and formal types of ECEC (précoce, Cycle 1) have positive but ...