Evaluation research is discussed as an applied social science that uses quantitative-comparative techniques to assess the effects of planned intervention. Focus is on the generally insufficient validity of treatment effectiveness research, and the relationship between research constructs and theory and their operationalization. (TJH)

The future of program evaluation is bright if evaluators do not ignore their roots in quantitative research. The current interest in qualitative approaches and the call for a "fourth generation" in evaluation should not override training in quantitative research. Qualitative research should complement, rather than replace, traditional…