Institutional repositories (IR) maintained by research libraries play a central role in providing open access to taxpayer-funded research products. It is difficult to measure the extent to which IR contribute to new scholarship because publisher self-archiving policies typically require researchers to cite the “version of record” of a manuscript even when an IR copy is accessed to conduct the research. While some studies report an open access (OA) citation advantage resulting from the availability of self-archived or “green” OA manuscripts, few have sought to measure an OA citation effect of IR separately from disciplinary repositories, including arXiv and PubMed Central. In this study, the authors present a bibliometric analysis examining correlations between search engine performance of items in IR, OA availability from different types of repositories, and citations. The analysis uses a novel, open dataset of IR access and usage derived from five months of Google search engine results pages (SERP) data, which were aggregated by the Repository Analytics and Metrics Portal (RAMP) web service. Findings indicate that making OA copies of manuscripts available in self-archiving or “green” repositories results in a positive citation effect, although the disciplinary repositories within the sample significantly outperform the other types of OA services analyzed. Also evident is an increase in citations when a single manuscript is available in multiple OA sources.