The conference on January 25–27 at Rochester demonstrated that considerable progress has been made in our experimental understanding of the fundamental properties of nucleons and mesons and their mutual interactions during the past year, but that theoretical insight into the meaning of these results still leaves much to be desired. This was the fourth in the series of annual conferences organized by Professor R. E. Marshak and jointly sponsored by a group of Rochester industries and the National Science Foundation. These informal sessions serve as a meeting ground for representatives from most American and several European laboratories actively engaged in high-energy nuclear physics and cosmic-ray research, and have proved extremely valuable both for clarifying the amount of progress already made and the outstanding problems yet to be solved. In view of the wealth of material discussed. I have singled out only a few topics for detailed discussion in what follows.