Medications for opioid use disorder (MOUD) including buprenorphine are effective, but underutilized. Rural patients experience pronounced disparities in access. To reach rural patients, the US Department of Veterans Affairs (VA) has sought to expand buprenorphine prescribing beyond specialty settings and into primary care. Although challenges remain, some rural VA health care systems have begun offering opioid use disorder (OUD) treatment with buprenorphine in primary care. We conducted interviews with clinicians, leaders, and staff within these systems to understand how this outcome had been achieved. Using administrative data from the VA Corporate Data Warehouse (CDW), we identified rural VA health care systems that had improved their rate of primary care-based buprenorphine prescribing over the period 2015-2020. We conducted qualitative interviews (n = 30) with staff involved in implementing or prescribing buprenorphine in these systems to understand the processes that had facilitated implementation. Clinicians, staff, and leaders embedded within rural VA health care systems located in the Northwest, West, Midwest (2), South, and Northeast. Qualitative interviews were analyzed using a mixed inductive/deductive approach. Interviews revealed the processes through which buprenorphine was integrated into primary care, as well as processes insufficient to enact change. Implementation was often initially catalyzed through a targeted hire. Champions then engaged clinicians and leaders one-on-one to "pitch" the case, describe concordance between buprenorphine prescribing and existing goals, and delineate the supportive role that they could provide. Sites were prepared for implementation by developing new clinical teams and redesigning clinical processes. Each of these processes was made possible with the active, instrumental support of leadership. Results suggest that rural systems seeking to improve buprenorphine accessibility in primary care may need to alter primary care structures to accommodate buprenorphine prescribing, whether through new hires, team development, or clinical redesign.