THE LONG-TERM GOAL OF CRIME CONTROL POLICY IS TO MINIMIZE CRIMINAL ACTIVITIES WITHIN SOCIETY WHILE PRESERVING CIVIL LIBERTIES. THE MISSION OF THE LEAA IS TO HELP STATE AND LOCAL GOVERNMENTS CONTROL CRIME AND IMPROVE THE QUALITY OF CRIMINAL JUSTICE AND THIS ENTAILS EVALUATION OF CRIMINAL JUSTICE AGENCY PROGRAMS. EVALUATING SOCIAL PROGRAMS, SUCH AS CRIME CONTROL, IS COMPLICATED AND DIFFICULT. MAJOR HINDRANCES CONCERN DATA: (1) FAILURE TO OBTAIN ON A NATIONWIDE BASIS ROUTINE, STANDARDIZED, AND ONGOING DATA REQUIRED FOR EVALUATION; (2) FAILURE TO MAKE EVALUATION PLANNING COINCIDE WITH PROGRAM PLANNING; (3) FAILURE TO ENFORCE THE EXECUTION OF EVALUATIVE DATA COLLECTION EFFORTS AGREED TO IN-GRANT APPLICATIONS; AND (4) FAILURE TO PROVIDE ADEQUATELY FOR SPECIAL DATA COLLECTION EFFORTS IN EX POST FACTO EVALUATIONS. SINCE EVALUATIVE RESEARCH IS ALWAYS COMPARATIVE, IMPACT CAN ONLY BE MEASURED AND EXAMINED AGAINST SOME STANDARD. THE EVALUATION DESIGNS MOST COMMONLY ENCOUNTERED ARE PRE-POST DESIGNS COMPARING THE SITUATION BEFORE AND AFTER TREATMENT, DESIGNS WHICH COMPARE THE SITUATION AFTER TREATMENT WITH THE SITUATION FOR SOME CONTROL OR COMPARISON UNIT THAT HAS NOT RECEIVED TREATMENT, AND BEFORE-AFTER DESIGNS WHICH PRESUPPOSE BASELINE DATA. FOR EVALUATIVE STUDIES OF CRIMINAL JUSTICE PROGRAMS, UNIFORM CRIME REPORTS, FBI DATA, AND VICTIMIZATION SURVEYS ARE USUALLY USED TO MEASURE CRIME RATES AND RECIDIVISM. THESE DATA SUFFER FROM A NUMBER OF PROBLEMS INCLUDING INACCURATE REPORTING, INCOMPLETE REPORTING, NONUNIFORM DEFINITION OF TERMS, ETC. A CASE STUDY OF DATA PROBLEMS IN THE HIGH-IMPACT ANTI-CRIME PROGRAM OF THE LEAA INDICATES THAT DATA PROBLEMS RELATE TO THE SPECIFICATION OF PROJECT INTERVENTIONS, CHANGES BETWEEN PROJECT INTERVENTIONS AND PREVIOUS WAYS OF ACCOMPLISHING OBJECTIVES, DETERMINATION OF PROJECT RESULTS AND THEIR ATTRIBUTION TO PROJECT INTERVENTIONS, AND THE LACK OF SUFFICIENT AND VALID DATA AND THE LACK OF PROPER PLANNING FOR NATIONAL AND LOCAL EVALUATIONS. RECOMMENDATIONS TO IMPROVE THE DATA COLLECTION AND ANALYSIS PROCESS ARE OFFERED. REFERENCES ARE LISTED. (DEP)