Increasing diversity in the teaching profession while simultaneously raising the selectivity of teacher preparation programs is not only possible but critical, a report from the Center for American Progress argues. The report, America Needs More Teachers of Color and a More Selective Teaching Profession, found a growing gap between the percentage of students of color and teachers of color — and that the lack of diversity among teachers may help to explain why students of color are suspended or expelled from school at disproportionate rates. Challenges for improving the selectivity of teacher preparation programs include the difficulty of determining appropriate academic criteria for such programs, as well as race-based achievement gaps in standardized and licensure tests. At the same time, the study found that in most states that raised the selectivity bar between 2006 and 2012, the diversity of undergraduate education majors grew. The report's authors conclude that states can improve selectivity without adversely affecting diversity and recommend that states require teacher preparation programs to meet higher standards for recertification.