Skipped two and a half grades (from halfway through 5th into 7th, then next year straight to high school), got a full ride to a good college, did quite well academically (and finished in four years - to counter elfkin’s example), and am currently on track to finish my masters at another decent school.
Academically, no troubles at all. I could most likely have skipped earlier and more, but the resources weren’t available to allow that.
Socially? I have to be totally honest and say that it honestly didn’t make much of a difference in my case.
I was the quiet weird one in K4 through 5th grade, and I was the *equally quiet and weird one *afterwards in that one year of middle school and all the way through high school.
Was I immature in those later years compared to my peers? It’s hard to tell. I was shy, introverted, and not particularly interested in live people.
IMPORTANT - This may be much harder and considerably different for boys than for me as a girl. Girls have a much easier time if their goal is to try to be total wallflowers.
I never got “adopted” by high schoolers, but I never got picked on either - just ignored. I wasn’t ready for relationships, but then no one offered one (nor was I interested in any of them because I thought they were all brainless), so that balanced out. I might not have been emotionally mature, but I also wasn’t heading out for riotous drunken parties like most of my schoolmates regularly did.
And really, that was ok with me. They were all boring, and none of them ever were interested in ANYTHING that I cared about, and from what I could tell, half of them were actually incapable of actually *thinking *about anything in the first place. I was that dork that *wanted *to get tutored by the hard teachers after class, because we could really get into the stuff that they couldn’t cover in class, because no one else was interested in learning it.
It wasn’t until I got to college that I found intellectually-stimulating friends at roughly my own age to become my own social group. It was like suddenly getting a pass into a mental heaven.
So, yes, skipping can cause problems with fitting in. If a kid is sufficiently mentally different, there are going to be problems fitting in ANYWAY, and perhaps fast-tracking that whole school experience will just make it pass quicker so they can start finding their own way as adults, which in my experience has been phenomenally more simple than it was while I was in grade school.
I would however say that it seems from friends and my own experience, that if you DO decide to skip, there are better places to do that than in kindergarten.
As always Y(or Your Kid’s) MMV.