HBCU Expansion Act of 2005 - Amends the Higher Education Act of 1965 to include Predominantly Black Institutions (PBIs) as eligible under title III part B provisions for strengthening Historically Black Colleges and Universities (HBCUs).
Defines a PBI as any institution of higher education that: (1) offers a bachelor's degree program, and meets title III eligibility requirements including a certain enrollment of needy students; and (2) at the time of application, has a student enrollment of at least 500 full-time students, at least 51 percent of whom are African Americans.