The purpose of this study was to examine the changes in financial aid and student enrollment at historically Black colleges and universities (HBCUs) after the U.S. Department of Education increased the credit history requirements necessary to obtain Parental Loans for Undergraduate Students (PLUS). The study used institution-level data to examine financial aid and enrollment changes at four-year non-profit institutions in 2012/13 (the first full academic year after the new credit standards were in place). Descriptive statistics summarize financial aid and enrollment changes at HBCUs and at non-HBCUs that enroll a comparable proportion of low-income students. Results indicate that PLUS loans declined substantially at HBCUs in 2012/13, and the decreases were not fully replaced by other types of federal financial aid. HBCUs also experienced larger declines in enrollment than other institutions in 2012/13, corresponding to the larger decline in PLUS recipients at HBCUs. Enrollment declines at HBCUs were especially large for first-year students. Nationwide enrollment decreased more for Black students than for students in other groups. The results in this report may help inform policymakers who are considering future rule changes to the PLUS program. Appended are: (1) Data and sample restrictions; (2) Supplementary tables on financial aid analysis; (3) Enrollment changes at public and private institutions; (4) Technical details of the enrollment prediction model; and (5) Changes in PLUS loans and enrollment at two-year and for-profit institutions. [To access the companion report "Changes in Financial Aid and Student Enrollment at Historically Black Colleges and Universities after the Tightening of PLUS Credit Standards. Stated Briefly. REL 2015-088," see ED555651.]