INTRODUCTION: This mixed-method study analyzes the self-archiving behaviors and underlying motivations of researchers at a Carnegie-Classified Doctoral - High Research Activity (R2) institution with significant increases in research activities. METHODS: A quantitative analysis of data provided by CHORUS, a multi-institutional open access (OA) infrastructure project designed to minimize the administrative costs of complying with federal public access mandates, was followed by semi-structured qualitative interviews with researchers to determine the underlying motivations for self-archiving research papers resulting from federal grant support. RESULTS: Fifty-one authors with federal research funding published seventy-nine journal articles. One-hundred and thirty-nine OA versions of these seventy-nine articles were intentionally made available by researchers across nine types of platforms, including and in addition to those provided by publishers. Interviews with ten investigators revealed motivators such as a dedication to public access to knowledge, learned behaviors in specific disciplines, and enlightened self-interest. Challenges included concern regarding confidentiality, confusion about intellectual property and funder requirements, administrative overhead, and integrity of the scholarly record. DISCUSSION: Despite concerns and a lack of an OA mandate and other drivers more commonly present at larger, more research-intensive universities, several researchers interviewed actively engaged in self-archiving article versions, not always with clear motivations. These findings have implications for both scholarly communications and collection development services. CONCLUSION: These quantitative and qualitative data informed the creation of three distinct personas intended to help librarians at similar universities design services in manners that align with investigator motivations.