Over the past 15 years, professional astronomers, their societies, and associated funding agencies have collaborated to improve astronomy teaching and learning at the introductory undergraduate level. Many nonscience majors and preservice teachers enroll in these introductory astronomy courses, thus meriting the focused attention. In this review of recent developments, issues, approaches, and resources, we describe and document key instructional assets that have been made available to college and university faculty who wish to enhance their teaching of introductory astronomy. We find that although faculty support has progressed intermittently, there exist numerous programs and resources that faculty can access to increase student engagement and learning in astronomy. As funding support for these various instructional assets have waxed and waned, the professional societies have served as vital anchors and agents for advancing the profession of astronomy education at the introductory undergraduate level. Our findings, though focused on astronomy education, can be applied to the practice of introductory undergraduate education throughout the Earth and space sciences.