Classical pulsators, such as RR Lyrae and Cepheid variable stars, have great utility in different areas of astrophysics, from stellar evolution, pulsation theory, galactic structure studies, distance measurement, and near-field cosmology. These standard candles illuminate our study of the Milky Way Galaxy and the Local Group through ground and space-based observations. These proceedings cover these topics, and delve into new and challenging puzzles these variable stars reveal. The papers in this volume discuss the new frontiers of astrophysics opened by classical pulsators and where researchers will blaze new trails in the 2020s.