This paper describes two geotechnical parameter estimation systems. These systems can assist in the estimation of soil parameters for slope stability analysis when adequate data are not available because of time or equipment limitations. The systems also provide an opportunity for crosschecking for consistency between the results obtained from different field or laboratory tests. The two correlation programs described in the paper are based on the same concepts. However, one has been developed using an object-oriented approach as part of a larger knowledge-based system for interpretation of geotechnical data developed at Durham University; the other has been developed in a spreadsheet environment as a module of an "Intelligent and Integrated Design Environment for Slopes (SlopeIDE)" developed at Istanbul Technical University. It is suggested that correlation systems show their real value when they are used with or within a knowledge-based system for geotechnical engineering applications such as slope stability, foundations or tunnelling.