Cosmic Ray particle production

The status of some popular models to simulate hadronic and nuclear interactions at Cosmic Ray energies is reviewed. The models predict the rise of all the hadronic and nuclear cross sections with energy and a smooth (logarithmic) rise of average multiplicities, rapidity plateaus and average transverse momenta with the energy. Big differences are found between model predictions partly already at energies, where collider data are available. It is argued, that at the highest energies data of the Cosmic Ray cascade can only be reliably interpreted by sampling the cascade using more than one model. The importance is stressed to put more effort into the models and especially a better understanding of the minijet component at the highest energies. Likewise, experimental data on particle production are needed at the highest possible energies, to guide the models