The 12th Annual Workshop on SIMS will be held in Gaithersburg, MD in April 1999. The goal of the workshop is to provide an informal forum for the interchange of information about SIMS. Sessions are typically devoted to methods of analysis, instrumentation and fundamentals. Special topic tutorial sessions are held on new and emerging aspects of the technique. This year's Workshop will deal with the practical aspects of secondary ion mass spectrometry. A selection of proposed special topic areas include fundamentals, ultra-shallow depth profiling, instrumental developments, biological and organic SIMS, geology, insulator analysis, quantification and applications. The format of the workshop is informal, with topics of interest to both the novice and experienced SIMS user. Both oral and poster sessions are planned. All participants are invited to submit an abstract of work to be presented at the conference. You are also encouraged to bring a few overhead transparencies illustrating novel applications of SIMS to present in discussions. This year's workshop will also feature instrumental users schools on Wed April 28, 1999. All major SIMS instrument manufactures will be represented. Open houses with hands on training will be available at NIST and the Army Research Lab on Thursday April 29, 1999.