Modeling and simulation are major assets in the engineering of systems of all types, in particular for production management problems. This section provides an overview of the basic aspects and key issues in modeling and simulation of agricultural production systems. Particular attention is given to the kind of structures, processes, requirements, and difficulties that have to be dealt with in the modeling of the interactive processes underlying management activities and biophysical components. Simulation can be used in combination with optimization techniques to find settings that optimize expected performance criteria; various such techniques are surveyed. The issue of calibration and validation of an agricultural production system model is also addressed.