The purpose of this analysis is to present a detailed overview of the current state of evaluation methodology in Organization Development. A detailed search procedure yielded thirty-five empirical studies in the OD field for the period 1959 to mid-1975. Each study was analyzed according to (1) research design; (2) data collection procedures; (3) subject characteristics; (4) treatment dimensions; and (5) data analysis approaches. Findings show that the overall quality of OD research methodology was spotty. Research designs were relatively strong with a large percentage of investigators using quasi-experimental designs. An excessive reliance on questionnaires as the sole data collection approach exists. Only a small percent of studies report using other quantified approaches. Most studies were conducted in one organization or in situations where the N’s for units of analysis larger than the individual were small (< 10). The heavy use of laboratory training intervention techniques was noted, although a strong shift from process to task orientation has occurred in recent years. Over 75% of the studies reported the use of statistical tests of significance. Although data analysis procedures are becoming more sophisticated, the vast majority of studies used very simple analytical techniques. Based on this analysis, a series of suggestions for improvement of methodological approaches to OD research is presented.