Given academia's frequent use of publication metrics and the inconsistencies in metrics across disciplines, this study examines how various disciplines are treated differently by metric systems. We seek to offer academic librarians, university rank and tenure committees, and other interested individuals guidelines for distinguishing general differences between journal bibliometrics in various disciplines. This study addresses the following questions: How well represented are different disciplines in the indexing of each metrics system (Eigenfactor, Scopus, Web of Science, Google Scholar)? How does each metrics system treat disciplines differently, and how do these differences compare across metrics systems? For university libraries and academic librarians, this study may increase understanding of the comparative value of various metrics, which hopefully will facilitate more informed decisions regarding the purchase of journal subscriptions and the evaluation of journals and metrics systems. This study indicates that different metrics systems prioritize different disciplines, and metrics are not always easily compared across disciplines. Consequently, this study indicates that simple reliance on metrics in publishing or purchasing decisions is often flawed.