The purpose of this research was to investigate the efficacy of professional development in changing two middle school science teachers' questioning to include more questions that require deeper student responses. The professional development was based on ICAP theory which proposes a framework for identifying cognitive engagement based on what is required of students. ICAP hypothesizes that Interactive and Constructive questions, such as those requiring inferential thought and collaboration, lead to deeper thinking and therefore stronger learning gains than questions that are more Active, Passive. Teacher questioning before and after the PD showed a marked improvement in increasing the number of questions that required students to make inferences about the materials. Student gain scores from tests on the lesson's content suggests a positive relationship between "constructive" questions and student learning. This paper also details a coding scheme based on ICAP that can be used to provide feedback on teachers' questioning. [This article was published in "Journal of Educational Research" (EJ1243452).]