This book describes our current knowledge of canopy photosynthesis that has accumulated over the last hundred years since the pioneering study of P. Boysen Jensen. The book provides a comprehensive analysis of plant canopy physiology, ecology and physics with emphasis on predictive modeling techniques. The book is divided into five parts covering hierarchy of canopy processes in time and space. Two chapters in Part 1 discuss the basic physical processes on light attenuation and energy transfer in plant canopies, while three chapters in Part 2 deal with the principle mechanisms of leaf gas-exchange regulation and the patterns and mechanisms of variations in leaf traits. Three chapters in Part 3 focus on whole-plant processes in plant canopies. Part 4 (in four chapters) describes how vegetation functions are assessed by modeling, eddy-covariance techniques, and remote sensing and forest inventory. Finally, three chapters in Part 5 discuss the relationships between canopy photosynthesis and other vegetation processes in plant stands.