Abstract: As organizations have clear goals and specific tasks, the psychology in organizations is different from that in general social context. The psychology and behavior in organizational contexts are affected by multiple factors at the levels of the individual, group, organization, and even society, organizational psychology scholars need to identify the relationships between these contextual variables and the targeted phenomena. This paper starts with the trend of contextualization in organizational research, and examples are used to illustrate the contribution of contextualization to theory building. Then, the multilevel issues in organizational psychology research are addressed, with an emphasis on the necessity of defining the level of constructs and theories. The underlying rationale of defining the level of theories is explained. Taking the research at the group level as the example, the paper addresses the methods of developing the group level constructs and the questions regarding measuring the group level constructs. Given that dependent variables at the individual level may be influenced by independent variables at both individual and higher levels, the paper describes multilevel theory in organizational psychology research. Recent organizational psychology studies published in top journals are cited to illustrate how to contextualize research and how to develop multilevel theories.

Key words: organizational psychology, contextualization, constructs at the group level, multilevel theories