Persons Excluded due to Ethnicity and Race (PEERs) remain underrepresented in university faculties, particularly in science, technology, engineering, math and medicine (STEMM) fields, despite increasing representation among students, and mounting evidence supporting the importance of PEER faculty in positively impacting both scientific and educational outcomes. In fact, the ratio of PEER faculty to students has been steadily dropping since 2000. In our case study, we examine the factors that explain creation of an unusually diverse faculty within a biology department. We analyzed nearly 40 years of hiring data in the study department and show that this department (the study department), historically and currently, maintains a significantly higher proportion of PEERs on faculty as compared to two national datasets. Additionally, we identify factors that contributed to hiring of PEERs into tenure and tenure-track positions. We observed a significant increase in the hiring of PEERs concurrent with the implementation of a co-hiring policy (p= 0.04) which allowed a single search to make two hires when at least one candidate was a PEER. In contrast, three key informants at sister departments reported that co-hiring policies did not result in PEER hires, but instead different practices were effective. In line with one of these practices, we observe a possible association between search committees with at least one PEER member and PEER hiring (p = 0.055). Further, the presence of particular faculty members (Agents of Change) on search committees is associated with PEER hiring. In this case study the combination of a co-hire policy based on the principle of interest-convergence to redress hiring inequities, along with the presence of agents of change, increased faculty PEER representation in STEMM departments.