This monograph contains a selection of papers presented at the Seventh Inter­ national Seminar on Model Optimization in Exploration Geophysics held at the Free University of Berlin, February 8-11, 1989. The papers presented here cover the different methods of synthetic and real data sets. The volume covers a wide spectrum of the subject from basic mathematics, general theory and computer implementation of methods to their practical applications. The first section of the book deals with the basic mathematics and general theory underlying geophysical data inversion. Papers presented here include those dealing with the solution of ill-posed inverse problems, constraint strategies in optimization, spherical spline approximation and the use of integral transforms in geophysical data inversion. The second section contains papers on the inversion of gravity and magnetic data. These papers cover such topics as the use of singular v;alue decomposition and space domain iterative inversion techniques in the study of gravity and magnetic anomalies. Also included here are papers dealing with the stochastic and statistical modelling of potential fields, mass density distribution inside the earth and the mapping of archeological sites through the inversion of magnetic field data.