General biology courses (for majors) are often transferred from one institution to another. These courses must prepare students for upper division courses in biology. In Colorado, a Biology Transfer Articulation Agreement that includes general biology has been created across the state. An evaluation was conducted of course grades in two upper division biology courses at University of Colorado Denver (UCD) (N = 2,129) based upon course grades in general biology and the type of institution where general biology was taken (2-year school, 4-year, in-residence at UCD, Advanced Placement [AP] credit, College Level Examination Program [CLEP] credit, or International Baccalaureate [IB] credit). Students who transferred general biology credits received lower grades in upper division biology courses and withdrew from upper division biology courses more frequently. The root causes for these disparities in student outcomes should be investigated further using demographic data and qualitative data. The study should be expanded to all Colorado institutions to ensure the effectiveness of the Biology Transfer Articulation Agreement.