The series of papers on climate change published in this issue are the result of the symposium “Environmental Change in Mesoamerica: Physical Forces and Cultural Paradigms in the Preclassic to Postclassic,” held at the 63rd Annual Meeting of the Society for American Archaeology in March 2000 in Philadelphia. The authors bring their expertise in paleoclimatological studies to bear on the Maya Lowlands and Highlands from the beginning of the Holocene to the Postclassic and modern times. The studies reveal that climate has changed during the past 4,000 years to a considerable degree that correlates in a reasonable way with archaeological periodizations. Several climate-change models are presented as an effort to understand better past cultural and natural events.