The paper aims to theorize and examine one of the earliest models of people-related antecedents of departmental IS performance. Based on the research gap about the effect of departmental managers on organizational IS performance and job performance theory as it is presented in the organizational behavior research field, this study develops a multilevel framework for people-related factors affecting departmental IS performance. The proposed multilevel research model was validated by using Hierarchical Linear Modeling (HLM) method with survey data of 283 department managers and 42 top managers in 42 companies with application of transaction processing systems. It suggests that top management support and the knowledge and attitude of department managers are the key determinants of departmental IS performance, and that in turn shapes company IS performance. This paper provides a pilot study on departmental IS performance by developing a multilevel model of people’s effects on departmental IS performance from organizational behavior and cross-level perspectives. Future research may attempt to integrate the constructs developed in this paper with those from other theories to develop and test more comprehensive models of departmental IS performance