High Excitation and Short Pulse Phenomena contains the proceeding of the Third Trieste ICTP-IUPAP Semiconductor Symposium on ""High Excitation and Short Pulse Phenomena"", held at the International Center for Theoretical Physics, Trieste, Italy on July, 2-6 1984. This book contains the keynote papers of the symposium and the contributions from the participants. It describes the non-equilibrium electron-hole plasmas in direct and indirect gap semiconductors; transport of plasmas and of hot carriers; and expansion velocities. The book also elucidates the screening effects involved in the exciton-plasma transition; the optical bistability and nonlinearity; and experimental techniques with short pulse spectroscopy. Other topics emphasized are the physical aspects of laser annealing and of melting at the highest excitation levels, as well as the results of high excitation and short pulse physics of quantum wells. The fast relaxation processes, as well as the carrier-carrier and carrier-phonon interactions are also explained. This material will serve as a source of information and reference, and will stimulate ways for further research.