Engineering is a way of thinking. It is a process of problem solving, a process of designing solutions, and a process of using what we know to make the world a better place. Over the past 20 years, engineering has made its way from solely a career for adults to a subject taught in K-12 schools across the country and embedded in most state standards. While early research on teaching engineering in K-12 schools focused on only the E in Science, Technology, Engineering, and Mathematics (STEM), today there is a focus on using engineering as a conduit through which to teach science, mathematics, technological skills, to truly integrate the four silos in the acronym, and teach 21st century skills like communication and collaboration. Guidelines have been established to help teachers choose or create engineering-infused lessons, and future research will focus on how to best prepare teachers, how to use engineering across all fields of science and mathematics, and how to use engineering to level the playing field for diverse learners and broaden participation in STEM careers.