Background: Nowadays, the confronting dichotomous view between experimental/quasi-experimental and non-experimental/ethnographic studies still exists but, despite the extensive use of non-experimental/ ethnographic studies, the most systematic work on methodological quality has been developed based on experimental and quasi-experimental studies. This hinders evaluators and planners" practice of empirical program evaluation, a sphere in which the distinction between types of study is changing continually and is less clear. Method: Based on the classical validity framework of experimental/quasi-experimental studies, we carry out a review of the literature in order to analyze the convergence of design elements in methodological quality in primary studies in systematic reviews and ethnographic research. Results: We specify the relevant design elements that should be taken into account in order to improve validity and generalization in program evaluation practice in different methodologies from a practical methodological and complementary view. Conclusions: We recommend ways to improve design elements so as to enhance validity and generalization in program evaluation practice.