When Days Are Numbered: Calendar Structure and the Development of Calendar Processing in English and Chinese Melissa K. Kelly and Kevin F. Miller University of Illinois at Urbana–Champaign Ge Fang Institute of Psychology, Chinese Academy of Sciences, Beijing, People’s Republic of China and Gary Feng University of Illinois at Urbana–Champaign Unlike English, Chinese uses a numerical system for naming months and days. This study explored whether this difference in naming affects the development of simple calendar calculation. Eight- and 10-year-old children as well as undergraduates in China and the United States were asked to name the day or month that comes a specified time before or after a given day or month. In each age group Chinese speakers primarily used calculation based on calendar names to solve these tasks, while English speakers primarily resorted to reciting the names. The magnitude of these differences was substantial; on difficult tasks Chinese fourth graders performed at speeds comparable to those of English- speaking adults. Implications for models of how linguistic structure affects cognition are discussed. © 1999 Academic Press Key Words: symbolic development; cross-cultural research; language and cognition; calendar processing. This research was supported by NIMH Grants K02MH01190 and R01MH50222 to the second author. The authors thank the students and staff of Leal Elementary School in Urbana, Illinois, and of the Beijing Institute of Foreign Languages Elementary School in Beijing, China. Renee Baillar- geon, Judy Deloache, Gregory Murphy, and Brian Ross provided helpful comments on an earlier version of this article. Special thanks are due to Shiou-yuan Chen and Xiuhong Cao for help with coding strategy data. Address correspondence and reprint requests to Kevin F. Miller, Department of Psychology, University of Illinois at Urbana–Champaign, 603 E. Daniel, Champaign, IL 61820-6267. E-mail: kevinmil@uiuc.edu. Journal of Experimental Child Psychology 73, 289 –314 (1999) Article ID jecp.1999.2503, available online at http://www.idealibrary.com on 0022-0965/99 $30.00 Copyright © 1999 by Academic Press All rights of reproduction in any form reserved. 289