Abstract. A technique for integrating spatial data of dissimilar type, scale, resolution and information content was developed. The technique, statistical overlay, calibrates statistics from one lower resolution data source against those from another sampled higher resolution source, A multi-variate inequality constrained least squares approach is used. The method was tested for use in estimation of deforestation in the tropics. Interpretation maps of Landsat Thematic Mapper imagery from the Instituto Brasileiro do Meio Ambiente e dos Rccursos Naturais Renovaveis (IBAMA) as well as an Advanced Very High Resolution Radiometer (AVHRR) mosaic of the Amazon prepared by the U.N. Global Resource Information Database (UNEP/GRID) Geneva, were used for data sources.