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. 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.Comment: 13 pages, LATEX, espcrc2.sty, 21 figures included as ps file