This study examined how quantity and quality of early childhood education and care (ECEC) are related to the socio-emotional adjustment of children born in Germany (30-48 months old, N = 395). Previous research focused on a small set of ECEC features, used broad measures, and yielded inconclusive results. We assessed ECEC quantity (age at entry, hours per week), process quality (CLASS Pre-K), structural quality (child-teacher ratio), and classroom composition (percentage of immigrant children). Controlling for child, family, and teacher characteristics, we tested main and interaction effects in regression analyses. Research Findings: More hours per week predicted lower adjustment only on specific indicators (hyperactivity, conduct problems) and only in classrooms with a high percentage of immigrant children or a high child-teacher ratio. In addition, a higher child-teacher ratio predicted more conduct problems, but only for children who entered ECEC at a very young age. Process quality did not predict adjustment. Practice or policy: In sum, this implies that German ECEC does not pose a major risk for children's socio-emotional adjustment, as only certain aspects of quantity and structural quality are linked to very specific socio-emotional outcomes under very specific circumstances.