The effects of ozone (O₃) stress on crop photosynthesis and leaf senescence were added to maize, rice, soybean, and wheat crop models. The modified models reproduced growth and yields under different O₃ levels measured in field experiments and reported in the literature. The combined interactions between O₃ and additional stresses were reproduced with the new models. These updated crop models can be used to simulate impacts of O₃ stress under future climate change and air pollution scenarios.