The working relationship of information systems (IS) professionals and end users is an ongoing source of both research and practical concern. This study employs Attribution Theory to examine the causal attributions IS professionals and end users make for successful and unsuccessful user-system outcomes—end user attempts to use an information system to get the information needed to complete system-dependent, work-related tasks. Eighty-six IS professionals and 122 end users participated. The results show no differences in the nature of IS professional-end user attributions for successful outcomes, but very significant differences between them following unsuccessful outcomes. Post hoc analysis indicates that for unsuccessful user-system outcomes, the causal attributions of IS professionals and end users who are cross-functional team members are significantly less divergent than the causal attributions of those who are not. The implications of Attribution Theory for IS professional-end user interaction are discussed.