Question: My son has been attending a great private school since his freshman year, but he is socially miserable. My husband and I would like to give him a happy senior year -- and since all of his friends attend the local private school, we would like to transfer him there. Will transferring senior year hurt his chances of getting into a good four-year college? His GPA has been a steady 3.8.
For starters, I'm going to assume that the local private school does have room for your son at this late date. If so, then certainly the transfer will not hurt your son's chances of getting into a "good" four-year school. But if you really mean, "Will it affect his college admission odds in any way and limit his options, especially if he plans to apply to Ivies or other hyper-selective colleges?" then the answer is an unsatisfying "maybe."
Grades, course selection, and SAT (or ACT) scores are typically the most important components of a student's application. If you believe that your son's grades will be comparable (or perhaps even better) in the new environment, where he's happy, then that is a vote in favor of the new school. Presumably, he will be able to transfer into the same level of classes at the new school that in was in at his old one. For instance, if he'd been okayed for AP Calculus at the old school, can he take it at the transfer school, too? But keep in mind that there may be some differences in the curricular offerings which could affect your son's course selection. For instance, if AP American History is offered to seniors only at the new school and your son already took it as a junior at his old school, then he might not be able to fit any AP History class into his schedule. Similarly, if he was planning to take Latin 5 this year but the new school doesn't offer Latin through the fifth year, then he might have to eliminate language or make another choice. You get the picture.
As for test scores, the school switch probably won't make a whole lot of difference there unless your son was planning to take a Subject Test in the fall in an subject that he will no longer be able to take at the new school ... e.g., the aforementioned Latin. (Seems like a long shot, but maybe that's the case.)
Here's where the transfer may be most likely to have a negative impact:
--If the local private school is not as renowned as the old school and if it doesn't have the same reputation for rigor that the old school enjoys, then the more selective colleges may not be as interested in its applicants as they might be in those who come from the most prestigious private schools.
--If your son has been elected to some leadership position at his old school for his senior year, then he will probably have to relinquish it as a newcomer, should he transfer. I imagine that many of those jobs were already finalized in the spring. Likewise, if he is an athlete, he might lose a starting role or playing time, if he transfers. If, however, the bulk of his extracurricular activities and hobbies are outside of school (e.g. community volunteering or theater, martial arts, writing poetry), then the transfer should make minimal difference.
--The teachers and counseling staff at the new school will not know your son well at application time, and this could impact his recommendations and perhaps the college choices that the counselor helps him to make. Ways to get around this include asking junior-year teachers for references, providing the new counselor with information about your son's achievements and strengths, and doing your own research into college options--or even hiring a private counselor.
Finally, even though your son is "socially miserable" at his current school, you don't want to be too quick too assume that he will glide seamlessly into the new school that his friends attend. While you know your son--and his friends--and can probably gauge this pretty accurately, do keep in mind that teenagers are ... well ... teenagers. The relationship that your son enjoys now as "the kid from the other school" could potentially change once he transfers. The novelty of having him around might wear off, or some of the gang might be threatened by your son's success with his schoolwork (or with the ladies??? ;-) ) Thus, it's conceivable that your son may not be as happy at the transfer school as you anticipate.
Bottom line: If your son continues to be a 3.8 student, wherever he enrolls, he is sure to have many "good" colleges to choose among. But being a newcomer in his senior year might make him a somewhat less strong candidate than if he hadn't transferred, especially at the most sought-after colleges (which, of course, may not be on his list in the first place). However, if you're convinced that your son will have a much more enjoyable and memorable senior year if he transfers, then I think that that's a small price to pay for his happiness.