THE BOOK IS DIVIDED INTO THREE SECTIONS. THE FIRST SECTION, OBSTACLES TO EVALUATION, PRESENTS PAPERS ON THE PAST, PRESENT, AND FUTURE PROSPECTS OF EVALUATION RESEARCH; THE IMPACT OF EVALUATIONS ON FEDERAL POLICY; GOVERNMENT CONSTRAINTS ON EVALUATION QUALITY; AND OBSTACLES TO EVALUATING HUMAN SERVICE PROGRAMS. THE SECOND SECTION IS DEVOTED TO PAPERS CONCERNED WITH CAUSAL INFERENCE OR THE INTERNAL VALIDITY OF EVALUATION DESIGNS. SUBJECTS DISCUSSED INCLUDE THE USE OF CONTROL GROUPS IN EVALUATIONS; THE CONTRIBUTIONS OF CAUSAL MODELING TO EVALUATION RESEARCH; METHODS TO ASSESS CHANGE; AND TIME SERIES DATA UTILIZATION IN PROGRAM EVALUATIONS. THE THIRD SECTION ON IMPROVING MEASUREMENT RAISES THE QUESTION OF HOW LARGE AN EFFECT IS NEEDED TO BE STATISTICALLY MEANINGFUL. IT EXPLORES THE IMPACT OF MEASUREMENT UNRELIABILITY ON THE POWER OF EVALUATIONS TO DETECT DIFFERENCES; THE CONSTRUCTION AND INTERPRETATION OF MEASURES IN DIFFERENT FIELDS; THE USE OF BEHAVIORAL SCALES OF JOB PERFORMANCE; AND HOW TO ASSESS COSTS/BENEFITS OF THE NEW HEALTH TECNOLOGIES. A FINAL SECTION ON THE ROLE OF EVALUATION RETURNS TO ISSUES RAISED IN THE FIRST SECTION--THE RELATION OF EVALUATION TO THE SOCIAL ORDER IN WHICH IT IS INEXTRICABLY EMBEDDED. PAPERS IN THIS SECTION DISCUSS WHAT EVALUATORS MAY CONTRIBUTE TO IMPROVING THE IMPACT OF DATA ON POLICY AND PRACTICE. SUBJECTS INCLUDE ASSUMPTIONAL ANALYSIS FOR STRATEGIC PROBLEMSOLVING, ORGANIZATION THEORY PERSPECTIVES ON EDUCATION PROGRAM EVALUATION, EVALUATION AND CHANGE. LIST OF REFERENCES ARE INCLUDED AS WELL AS SHORT BIBLIOGRAPHIC ESSAYS ON THE AUTHORS OF THE PAPERS. (MJW)