The relationship between structural quality and process quality in early childhood education and care (ECEC) has been addressed in several studies. However, the findings are not conclusive. The present study was conducted in the Netherlands, which has a strongly regulated mid-quality ECEC system regarding structural aspects, with still considerable variation in process quality. The study employed a multi-method approach and extended the existing research in two ways. First, both observations of teacher–child interactions as well as teacher-reported developmental and educational activities were included as indicators of comprehensive emotional and educational process quality constructs. Second, to examine the relation between process quality and structural quality, commonly studied structural quality characteristics were complemented by less frequently studied measures of the professional development activities and education programs implemented at the centers. Results indicate that group size and child-to-teacher ratio are not related to emotional and educational process quality in the Dutch ECEC system. Teachers’ formal pre-service education has a positive, but small association with emotional process quality. The use of an education program and professional development activities at the center show the strongest associations with emotional and educational process quality. Implications for policy and practice are discussed.