I would very much appreciate your comments about this. Thank you.
Most studies don't support the practice of retention, especially for children with learning disabilities. The focus should be on meeting a child's needs in a developmentally appropriate setting (e.g., his own grade), but this is sometimes very difficult. Since your son seems to be benefiting from the reading instruction he has been getting, the school may have felt that holding him back would give him the time he needs to "catch up." This is good news, since it means that there is probably no underlying problem (such as a learning disability) that is getting in his way. He just needs more time and practice. Unless he's upset by spending another year in the same grade, then retention may help give him the skills he needs to be successful in the coming years.