Poorly structured policies implemented over the past few decades by states and cities are threatening retirement security for public school teachers, according to a new report published by Bellwether Education Partners.

In "Friends without Benefits: How States Systematically Shortchange Teachers' Retirement and Threaten Their Retirement Security," authors Chad Aldeman and Andrew J. Rotherham estimate that half of all Americans who teach in public schools won't qualify for even a minimal pension benefit, and less than one in five will remain long enough to earn a normal retirement benefit.

The report found that in Maine, 86.1 percent of teachers will not qualify for a pension, and in the District of Columbia four out of five beginning teachers will not. Only about 25 percent of teachers will qualify in Mississippi, Pennsylvania, New Hampshire, and Hawaii, while fewer than 35 percent of teachers will stay long enough to qualify for a pension in Florida, Nebraska, Indiana, South Carolina, New Mexico, Ohio, Georgia, and North Carolina.