Thirty-two states have passed legislation requiring third-graders to be able to read before promotion to the fourth grade. The Encyclopedia of Educational Research is less enthusiastic, noting that retained pupils show some gains for three years, then no gains.
The legislation ignores immaturity and poverty, with kids born in poverty lacking access to food, medical attention and dental care. However, one hopeful sign is the Affordable Care Act, which funds clinics on school sites offering health care for the uninsured poor, adults and children. This will do more to reduce retention than any legislation.
Too, lack of teacher preparation may cause retention. Example: My great-granddaughter, was retained in second grade because she got zero on state tests along with nine others out of a class of 20, was enrolled in the tutoring club and nine months later read at third-grade level. Today, she's a junior at Downey High looking forward to college.
Cost is a factor in retention. I read that the cost per pupil is $10,000 a year. An extra year for 10 pupils adds $100,000 to a school budget. Legislators must think that all pupils are like Garrison Keillor's in Lake Wobegon all above average.