Kevin: The structure of SF 3 is one header file plus 76 (!) data files, none with more that 250 fields, to handle the 16,520 fields in the 405 tables for Census Tracts and above. There are "only" 5558 fields in 281 tables for Block Groups. Each file has all summary levels mixed together, so you have to search each file that has the tables you want to look for the block groups or other areas you want. TransCAD and Maptitude users have it a lot easier. TransCAD users get the SF 3 Data CD for their state free as part of their maintenance agreement, plus the State Data CD with Block Group and other boundaries for their state. Maptitude users (or TransCAD users that want other states) can buy these CDs for $195 each. Nationwide Census Tracts, ZCTAs, counties, MSAs, etc. come with both TransCAD and Maptitude. The SF3 Data CDs have all 77 files merged, then split into each summary level: Block Groups, Census Tracts, etc. With the Table Chooser for SF 3, an add-in to TransCAD and Maptitude, you can easily pick the geography and tables that you want, and output a geographic file (with the tables attached) or just a tabular file. SF 3 Data CDs are being released as the Census Bureau releases the states. 12 states are out, and seven more are due tomorrow. For more information, please visit (http://www.caliper.com/DataCDs/SF3DataCD.htm). Peter ---------------------------------------------------------------- Peter Van Demark Director of GIS Products and Training Phone: 617-527-4700 Caliper Corporation Fax: 617-527-5113 1172 Beacon Street E-mail: peter(a)caliper.com Newton MA 02461-9926 Web site: http://www.caliper.com