“Mesoamerican Cultural Astronomy and the Calendar” is a Special Section including articles that explore portions of Mesoamerica where astronomy and calendars were studied by Indigenous peoples. Scholars who are well known for innovative work in astronomy, such as Aveni, as well as Pineda de Carías, Rivera, and Argueta, consider topics that fall under the rubric of cultural astronomy. Epigraphers or experts in hieroglyphic writing, like Justeson and Vail, deal in explicit ways with issues related to calendar development. An art historian, Milbrath, weighs in on the meaning of astronomical and calendar themes using important documents incorporating both images and texts. An archaeologist, Dowd, and an architect, Carrasco, discuss architectural complexes with orientations significant in horizon-based astronomy. This rich cross-disciplinary collection of articles debuts new discoveries that interweave astronomy, time measurement, and ritual behavior commemorating cycles of death and rebirth among Maya peoples who lived between a.d. 225–1519 in what is now Honduras, Belize, Mexico, and Guatemala.