This volume is the proceedings of a NATO Advanced study In- stitute held at the Hotel do Parque in Viana do Castelo (Portugal). The school was directed by Roger Kelly (U.S.A.) and M. Fernanda da Silva (Portugal), and the organizing committee consisted of Harry Bernas (France), George Carter (U.K.), Paolo Mazzoldi (Italy), and Edmund Taglauer (Germany). The dates were 24 August to 4 September, 1987. The School was conceived to satisfy the needs of those who study particle-surface interactions at high fluence, i.e. under conditions leading to chemical, electronic, mechanical, and structural changes rather than just doping. This community of scientists is surprisingly large even though demonstrated ap- plications are still relatively few. As such, the community is as much engaged in pure research as In applied work. It is very highly developed in Western Europe but less so in North America. This interesting state of balance has a number of causes, not the least of which is the way in which science is funded in North America: public relations plays a large role.