The goal of this chapter is to demonstrate how one can predict leaf photosynthetic behavior as a function of environment experienced and physiological status. Stomatal and CO2 flux resistances have already been discussed. Here we will consider how biochemical-physiological models are derived and how they are meshed with flux resistance models to create leaf photosynthesis models. In several instances, we first present a model and then discuss the validity of model assumptions. One must not be misled by immediate objections that come to mind for the functions proposed. These should be pondered at the end of sections. Aspects of leaf photosynthesis models, like temperature acclimation and the developmental effects that have as yet received little attention, are discussed.