This volume contains 252 contributions presented as plenary, invited and contributed poster and oral presentations at the 11th International Conference on Secondary Ion Mass Spectrometry (SIMS XI) held at the Hilton Hotel, Walt Disney World Village, Orlando, Florida, 7 12 September, 1997. The book covers a diverse range of research, reflecting the rapid growth in advanced semiconductor characterization, ultra shallow depth profiling, TOF--SIMS and the new areas in which SIMS techniques are being used, for example in biological sciences and organic surface characterization. Papers are presented under the following categories: aeo Isotopic SIMS aeo Biological SIMS aeo Semiconductor Characterization Techniques and Applications aeo Ultra Shallow Depth Profiling aeo Depth Profiling Fundamental/Modelling and Diffusion aeo Sputter--Induced Topography aeo Fundamentals of Molecular Desorption aeo Organic Materials aeo Practical TOF--SIMS aeo Polyatomic Primary Ions aeo Materials/Surface Analysis aeo Postionization aeo Instrumentation aeo Geological SIMS aeo Imaging aeo Fundamentals of Sputtering aeo Ion Formation and Cluster Formation aeo Quantitative Analysis Environmental/Particle Characterization aeo Related Techniques These proceedings provide an invaluable source of reference for both newcomers to the field and experienced SIMS users.