Avenue programming and Dialog Designer were used in ArcView GIS 3.1 to develop screening tools into a complete application for site suitability analysis. A landfill siting application was developed, but the program is being expanded for more general use. A table can be created of criteria that aren't completely screened out with the initial restrictions, but can still be used to further pinpoint the best landfill site. This data is formatted and sent to a multicriteria decision analysis algorithm to determine the best overall location, and results are shown back in ArcView GIS. Criteria include required landfill volume (calculated from user input of readily available information), proximity to lakes and rivers, proximity to habitat and endangered species, distance to population centers, soil suitability for landfill placement and cover, zoning, area available, and land cost.