The use of a mail-out, mail-back procedure for conducting the pretest is explained, and statistical tabulations in the form of charts, graphs, and tables show the socioeconomic profile of New Haven, including a rising nonwhite population, increased family instability, and overcrowded housing. An examination is made of New Haven police recordkeeping procedures in the areas of complaint activity, arrest activity, and motor vehicle accident data. Court records for New Haven arrests are also examined. A manual experiment was conducted to match court records with arrest records and with individual schedules obtained during the using block face and person-matching procedures. The special tabulations for the 100 percent and 25 percent data are summarized and provide a description of New Haven on a tract and block basis. Also, the Dual Independent Map Encoding file system was developed to create a geographic base file for mapping and to relate local information to census data. The potential uses of census data for law enforcement are explored, especially in the areas of a computer look-up program, data analysis for forecasting police services needs, and computer output display. Suggestions are made for the 1970 census to include procedures for block face information gathering. Appendixes include over 90 references, tabulations, and census tract and block equivalents, 1960-67. A list of tables and illustrations are also included.