In scientific and academic circles, the value of Google Scholar as an information resource has received much scrutiny. Numerous articles have examined its search ability, but few have asked whether it has the accuracy, authority and currency to be trustworthy enough for scholars. This article takes a look at reliability factors that go into Google Scholar citation counts, selection of resources, and its commercial partnerships. Research data culled from correspondence with Google Scholar, analysis of citation metrics, metadata and search processes, and an appraisal of its strengths and weaknesses compared to other science-specific indexes led to the conclusion that Google Scholar may be useful for initial and supplemental information gathering, but lacks a deeper reliability than other existing services currently provide scholars. Advice is offered to science librarians about how to regard Google Scholar as a research tool. (Contains 1 table.)