While there is a considerable body of research demonstrating benefits of book reading, the quality and depth of engagement children experience while reading is essential to ensure positive reading experiences and outcomes. In this article we describe four dimensions of reading engagement: behavioral, cognitive, affective, and social, illustrating how each dimension is essential to ensure children benefit from the rich and diverse experiences that books have to offer. We next share a new scale, developed with input from researchers, teachers, and children, for teachers to use to measure children's reading engagement and support their students to get the most out of their reading experiences. We end with practical ideas for teachers to use the scale to inform instructional practices.