This intervention study aimed to foster and assess early childhood education (ECE) student teachers’ professional competence at the beginning of their second year in Finnish higher education. A study module on child development and ECE pedagogy provided the students with knowledge and practice in identifying, implementing, and reflecting on high-quality interactions with children. The students’ video-recorded picture book reading interactions with two preschool-aged children were assessed using the Classroom Assessment Scoring System (CLASS) Pre-K tool. The broad domain-level analyses showed high-quality emotional support and classroom organisation, but the quality of instructional support was relatively low. Behavioural-level analyses revealed that the students predominantly asked simple questions; they rarely posed complex questions or provided extensive feedback, and other types of discussions to boost children’s higher-level thinking and language use were practically absent. After the study module, student teachers’ self-reported closeness with children increased and conflict decreased. The findings are discussed from the perspective of fostering and assessing higher-quality instructional support in teacher preparation programmes.