EVALUATION RESEARCH HAS NORMALLY BEEN GUIDED ONLY BY THE QUESTION OF A PROGRAM'S EFFECTIVENESS, NOT BY ASKING WHAT IT WAS ABOUT THE PROGRAM THAT MAY HAVE HELPED TO PRODUCE THE DESIRED RESULTS. CONCEPTUAL AND METHODOLOGICAL DIFFERENCES BETWEEN BASIC SOCIAL SCIENCE AND EVALUATION RESEARCH ARE HIGHLIGHTED IN ORDER TO DIFFERENTIATE BETWEEN PAST APPROACHES OF THESE TWO TYPES OF RESEARCH. TWO EXAMPLES ARE CITED IN WHICH THE EXAMINATION OF CONDITIONS UNDER WHICH CERTAIN OUTCOMES MAY BE EXPECTED GUIDES THE RESEARCH EFFORT. THE FIRST EXAMPLE OF THIS APPROACH IS THE BALTIMORE LIVING INSURANCE FOR THE EX-PRISONERS (LIFE) PROGRAM SPONSORED BY THE U.S. DEPARTMENT OF LABOR. THE PURPOSE OF THE PROGRAM WAS TO DETERMINE WHETHER PROVIDING NEWLY RELEASED PRISONERS WITH FINANCIAL ASSISTANCE WOULD REDUCE RECIDIVISM. AT THE OUTSET, THE PROGRAM VARIABLES WERE CLEARLY DELINEATED (FINANCIAL ASSISTANCE AND JOB SERVICE); THE MAIN DEPENDENT MEASURE WAS IDENTIFIED (WHETHER THE MEN WERE ARRESTED DURING A PRESCRIBED TIME); A RATIONALE FOR PROGRAM EXPECTATIONS WAS PROVIDED; CONDITIONS WERE SYSTEMATICALLY VARIED FOR THE PROGRAM, AND THE RESULTS DOCUMENTED. THESE SYSTEMATIC VARIATIONS PERMITTED A COMPARATIVE APPRAISAL OF THE EFFECT OF CERTAIN PROGRAMMATIC ELEMENTS ON THE OUTCOME MEASURES. THE SECOND EXAMPLE CITED IS AN EVALUATION EFFORT BY THE CRIMINAL JUSTICE RESEARCH CENTER, INC., IN ALBANY, N.Y., FUNDED BY THE NATIONAL INSTITUTE OF LAW ENFORCEMENT AND CRIMINAL JUSTICE. THIS ORGANIZATION IS EVALUATING RESTITUTION PROGRAMS SPONSORED BY LEAA IN SEVEN STATES. THE EVALUATION EFFORT WILL ATTEMPT TO DEAL WITH QUESTIONS AS TO WHEN AND FOR WHOM RESTITUTION IS EFFECTIVE. THE VARIABLES WILL INCLUDE TYPE OF OFFENDER AND TYPE OF VICTIM. OUTCOME MEASURES WILL FOCUS ON BOTH OFFENDER AND VICTIM, INCLUDING OFFENDER'S SUBSEQUENT CRIMINAL RECORD AND VICTIM SATISFACTION WITH REPAYMENTS. AN ANALYSIS OF THE TWO APPROACHES REVEALS DISCREPANCIES IN METHODOLOGY; HOWEVER, BOTH PROGRAMS CONSIDER SPECIFIC PROGRAMMATIC ELEMENTS AND THEIR INTERACTIONS IN INFLUENCING RESULTS. DETERMINING THE EVALUATION DESIGN AND IMPLEMENTATION STRATEGY AT THE OUTSET OF THE PROGRAM IS ESSENTIAL. ASKING THE QUESTION, 'UNDER WHAT CONDITIONS WILL THE PROGRAM BE EFFECTIVE IN ATTAINING A DESIRED OR IN PREVENTING AN UNDESIRED RESULT?' IN EVALUATION EFFORTS, MAY ASSURE OBTAINING THE THE MAXIMUM AMOUNT OF INFORMATION. REFERENCES ARE INCLUDED.