Evaluators of the effectiveness of treatment and rehabilitation programs in the field of crime and delinquency should have at their disposal a large body of theoretical knowledge, which should have resulted from the numerous treatment and rehabilitation programs of the last decade, especially programs for juveniles. Unfortunately, there is no clear evidence overall to support the effectiveness of any specific treatment approach in terms of reduced involvement in criminal behavior. It is suggested that the lack of comparability in treatment and service program evaluations is the main factor limiting the utility of program evaluation studies. Conceptually, the lack of comparability is the result of nearly universal absence of a rationale linking program objectives to expected outcomes. Operationally, it is the result of few attempts to replicate earlier studies and the widespread practice of researchers to develop their own unique measures of key variables. After defining studies comparable when their findings lend themselves to being aligned, integrated, or combined with those from other studies into generalizations, the sequence involved in a theoretical/experimental approach to program development and evaluation is detailed. A tutorial program for delinquent youth is described to illustrate the concept that projects with a theoretical rationale can often be evaluated on the basis of more than one criterion of success. In this case the program was rated successful in terms of its having improved the youths' academic skills, although such improvement did not appear to impact on delinquent behavior or rearrest, as originally hypothesized. The need for theory-based evaluations is stressed, because a theoretical rationale provides a more abstract set of concepts through which cross-program comparisons are facilitated. Increased use of established measures is advocated, a number of key theoretical variables used in previous crime and delinquency research are identified. A noncomprehensive catalog of variables and measures is presented, representing such theoretical perspectives as opportunity theory, social control theory, labeling theory, and differential association theory. Major concepts derived from these theoretical perspectives are specified in tabular form. In addition to the Catalog of Crime and Delinquency Impact Scales, endnotes and 65 references are appended.