Crop models and decision tools are increasingly affecting agriculture. Various forms of information technology are being adopted in agriculture as modern technology advances. To review research achievements and identify new directions in crop modeling and decision support, an international symposium on crop modeling and decision support was held in Nanjing, China in April, 2008. The main purposes of this symposium were to exchange the state-of-the art of current modeling and simulation approaches, as well as recent progress on crop models and decision support systems leading to on-farm applications; to explore future directions needed for advancement and potential opportunities for team collaboration. The symposium was successfully held with a grand gathering of about 120 scientists and researchers from more than 20 countries. Over 100 abstracts and 40 papers were presented at the meeting, and selected papers were combined into this book as the symposium proceeding, in addition to some papers submitted for journal publication. Thus, the present book is a main output of the symposium, and should be useful for the scientists, graduate students and management specialists in the areas of crop modeling and decision support. This proceeding book covers cutting-edge results on crop growth modeling, decision support system and model-based information technologies for crop growth prediction and production management. It covers the subjects of crop and soil process modeling, plant architectural modeling, climate change modeling, crop productivity modeling, simulation model development, model-based decision support systems (DSS), applications of crop models and DSS, integration of crop models with other information technologies. We would like to express our gratitude to all the participants for their participations and presentations at the symposium. Great thanks go to the Academic Committee of the symposium for their great efforts and hard work, to Drs Qi Jing and Liang Tang as the secretaries of the symposium, and to Drs Yan Zhu, Yongchao Tian, XiaoJun Liu and Xia Yao for their hard work during the symposium. We also thank the sponsors for their generous supports making the symposium successful.