This review study includes 19 articles from 2016 to 2021 focusing on in-service science teachers' professional development targeted to promote student conceptual understanding. The present study is guided by the following research question: "What characterizes high-quality in-service science teachers' professional development targeted to promote student conceptual understanding?" The review indicates that such classroom practices as modelling, questioning, and arguing from evidence are perspective ways to develop student conceptual understanding in science classrooms. A mixture of input, application, and reflection; long-term involvement of participants; focus on the question how to foster transfer from teacher professional development into participants' everyday work characterize high quality teacher professional development interventions that develop and support inquiry practices. Results suggest that teacher professional development that is sensitive to teacher learning needs is a way to develop student conceptual understanding. [For the full proceedings, see ED620289.]