Many adults who have been retained say it was the worst event in their lives. Of course, retention can be successful, especially when it is strongly supported by parents and done in the early grades. It must also put children in a program that is different from the failing year. Unfortunately, it is almost impossible to predict when retention will be successful.
You need to spend some time analyzing your son's situation very carefully in order to come up with the best solution. How old is your son? Did he start school early? How is his vision? How is he doing in his other subjects? And most important of all: Why is he having reading problems and how can he be put on the road to becoming a successful reader? We recommend that you ask the school to evaluate your son's reading so that he can receive the specialized help he needs.
Meanwhile, it is quite possible that things can be turned around fairly swiftly for your son by special help at school and home as well as a rigorous effort this summer to improve his reading. You can enroll him in a summer reading program at his school, a local college, or a commercial learning center or get him a tutor. A commercial phonics program might be helpful. Ask the teacher for suggestions, and begin helping him at home.
Your child's reading problems will not go away without some specialized help. You can't sit back and expect him to become a good reader just because you decide to have him repeat first grade.