The NAFO Scientific Council Special Session of September 2003 was the Workshop on Mapping and Geostatistical Methods for Fisheries Stock Assessment. The objective of the workshop was to provide participants with the basic understanding of geostatistical concepts and methods, and provide tools to apply this knowledge to fisheries stock assessments. The instructors introduced freeware mapping and geostatistical software. Two sets of data were used for the lessons and demonstrations: the Canadian spring bottom trawl survey data from 1996 to 2002, and information from the yellowtail flounder commercial fishery on the Grand Bank from 1996 to 2002. The visualization, analysis and modeling of spatial data using Geographic Information Systems (GIS) were presented (e.g. Ocean Data View (ODV freeware), SPAN (Spatial Analysis System) and ACON (A CONtouring package). Surface (map) generating techniques were demonstrated using the various software packages. Geostatistical concepts and methods related to kriging, and methods for analyses using basics of the "R" software package were described.