Purpose: The purpose of this paper is to identify how intervention research weighed in nonintervention research in the field of human resource development (HRD) by examining the number, citation frequency and use of experimental studies in HRD academic journals. Design/methodology/approach: A total of 2,700 articles published between 1990 and 2014 from "Advances in Developing Human Resources" ("ADHR"), "European Journal of Training and Development" ("EJTD"), "Human Resource Development International" ("HRDI") and "Human Resource Development Quarterly" ("HRDQ") were reviewed and analyzed to identify 91 experimental studies in the field. Findings: The total citation frequency of the 91 articles was 1,100 (14 from "ADHR," 222 from "EJTD," 56 from "HRDI" and 808 from "HRDQ"). The authors reviewed the 1,100 subsequent studies that cited 91 experimental research studies and coded them to identify the research methods that each article adopted and to determine whether the studies used the citation to make causal statements. As a result, the authors found 459 causal statements from 1,100 citations. In particular, they identified the citation frequency of the causal statements used in nonintervention research to examine how often nonintervention studies used causal statements from intervention studies. Research limitations/implications The results of the citation frequency could be different according to the search engines and timeframes. Books, technical reports, non-English studies, non-academic articles and inaccessible articles were not considered in this study. Theoretically, this study aimed to illuminate the magnitude of HRD experimental research conducted over 25 years and to what extent it influenced non-experimental studies. In addition, this study emphasized the importance of using the causal statements from experimental research to improve empirical validation in other studies. Practical implications: When HRD practitioners need to identify alternative interventions to replace previous ones or to justify the use of specific interventions, they could consider causal statements from empirical studies as valid evidence. Further, HRD practitioners might collaborate with researchers to receive more direct and relevant information from experimental research. Originality/value: Significantly, this study provides an integrative review of experimental research conducted in the field of HRD in terms of the number, citation frequency and proportion of using experimental research. An additional contribution is that it summarizes the research methods used in HRD studies over 25 years.