First, keep in mind the students chosen to be the “face/voice” of the school are among the most outgoing, comfortable speaking in large groups etc. kinds of kids – not everyone is that kind of kid, and that’s ok. Also, you are seeing the “external” view of those kids, and I’d bet their own parents might tell you a different story of their kids’ phone calls home worrying about things, so it is sort of like comparing apples and oranges – you know your own kids’ struggles, but only see the “finished” product of other kids. Finally, yes, your girls will do wonderfully! It is so much fun to watch kids mature and become their adult selves over the years of college.
I suspect they will be fine. Most students are. Yours sound very capable and I wouldn’t worry.
That said, a big pointers to watch out for is not getting out and getting involved. Even introverts need to get involved in something that fits them to feel their best. If they don’t, they often feel something is “wrong” with them (“everyone else knows how to do this except ME”) and that’s a road that can lead to a poor ending.
College is new to all (essentially all). Extroverts tend to naturally try to find their tribe. Introverts may pull back (or may surprise you/parents by doing just fine). A good RA will see that all students get involved - BUT - not all RAs are into doing the job well. As a parent, keep some contact. Listen to everything. Rejoice with them as they discover cool things and mainly listen when they encounter the typical problems they need to learn to deal with. Only intervene if a problem REALLY seems to warrant it OR if the student is pulling back and not stepping out of their dorm room (or inviting others in). In that latter case, really suggest looking at the signs for clubs to find an interest and trying it out. Sometimes study groups work too. They don’t have to stay if they don’t like it. They only need to try it to see.
Their interests may be the same as they had in high school or 100% different. It doesn’t matter. It only matters that they find a (nice) group (or two+) they can feel they fit in with. Encourage them to try something else if all you hear is negative. Introverts sometimes really do need the extra encouragement until they get rooted, then you’ll see them bloom just fine.
Again, my bet would be that yours are just fine, but I do see the results when that doesn’t happen, so offer my two cents to all reading. Sometimes even really top students at school seem to miss a connection at college. If connections are never made… it’s rarely good and sometimes horribly bad. If it doesn’t happen freshman year, it’s very worth transferring to a better fit school. (Most colleges have a tribe for everyone, but again, there are some who - for whatever reason - don’t find or feel they fit in with that tribe.) They don’t need to have it found the first week (or month - or sometimes even semester), but by the end of the first year it seems critical.
In general, I see high school students of all social levels leave for college and really cool adults come out of it - even those who have no interest in being part of “come to my school” groups.
Are your kids concerned about going? Or is it just you? Are they just introverted, or do they need a little more time to grow up? If they need a little more time, what would they and you think about a gap year?
If your kids are generally on track and you’re just nervous, it sounds like they picked really terrific schools where they can gently grow.
Agree that it’s critical that they form a social network at school. I think it’s @bopper who has a post about what kinds of things to do to network. One thing they can do is try to find out in advance what clubs there are, and make contact with those clubs. Definitely see if the schools have a pre-orientation where kids show up a couple of days earlier to do a certain activity like community service or outdoor club etc. and have them do that if it’s an option. Also most schools have admitted students FB pages. Have your kids join them and get together with other admitted students in your geographic area for lunch etc so they can make friends before they even step foot on campus.
Here’s a little behind the facade for you - My DS is a serious intellectual who loves to discuss all kinds of topics, he competes in extemporaneous speaking, is a member of two academic teams and has a very active social life within his friend’s group. He’s seemed so excited about going to college and I thought he was completely confident. However, he was filling out a survey from the college and it asked him to rate how prepared/confident he felt for college and I was completely shocked that he put two notches below completely confident! My friends always remark on how confident he is and how will have no trouble adjusting to college. But he told me “I just don’t really know what to expect.” So your daughters will be in good company as even those kids who seem confident on the outside might have doubts and concerns on the inside. Remember all the other Freshman will be going through this the first time too. I think it is an excellent choice to go to a small LAC for introverts, we are targeting these school for DD who is an introvert.
@RandyErika – I think that while you are right to be concerned, it’s also important to keep in mind that parents tend to have a restricted view of their own kids which often makes it difficult to see the full potential. One big part of the college growth experience is simply that the child no longer lives at home, under the watchful eyes of the parents. It is a new level of freedom that is often very empowering. No curfews, no asking permission to attend a party or hand out with friends or participate in evening activities --(even on a school night!) — and also no one picking up after the student, or asking whether homework has been done-- no one to question or judge their choice of a romantic partner or a casual date - and an array of potential new social and participatory opportunities that weren’t even on the student’s radar before. So kids do change, and being outside the orbit of mommy & daddy is a big part of that change.
In your daughters’ situation, there is one more element: no longer being in the shadow of the other twin, or being defined by the other twin. If they are identical, all the more empowering. How many times in their lives have they simply been referred to as “the twins”? or dealt with teachers who kept mixing them up? Or who expected them to have the same innate talents? If they choose different colleges, then for the first time in their lives they will truly feel like individuals, making friends with kids who don’t even know they have a twin unless told, and never again encountering a teacher whose expectations are shaped by the accomplishments of the other twin.
And of course some students struggle with that, and some kids aren’t ready – and can get into trouble. But I think many more thrive and grow – and many of your worries may be more of the parental angst of letting go. So take a step back, and keep in mind that the moment you drop each daughter off at her respective campus and drive away, the cord will have been cut.
Great responses above. I just wanted to empathize with the OP. I’m in the same boat with my DD. She’s exceptionally introverted and I’ve posted elsewhere the issues she’s had. Take heart from reading the comments about how they can blossom when given a sense of freedom. And really try and remember that when they call home with worries or woes, you’re just the support sponge that’s supposed to soak it all in and lift their spirits. I’m dreading that piece of it, but at least I’m prepared! 
Also I’ll just add one of my DD’s friends from high school last year was one of triplets, and each sister went off to a different college, each in a different state! They’re doing fine, so take comfort. All will be well.
Thanks to the additional posters since my last comment. All your perspectives are helpful and appreciated.
Yesterday’s accepted students day at Ursinus helped in a number of ways. D2’s positive feelings about the campus, the other prospective students, and the English/Creative Writing department reinforced her enthusiasm. Apparently the school mascot sat next to her during a student only session. She had a good laugh and managed a fist bump, despite having woken that day with the onset of an energy sapping cold. After a brief discussion today, she pulled the trigger and we deposited - go Bears!
D1 also likes Ursinus - and her sister - but she was thoroughly unimpressed with the art department, despite the obvious passion of its faculty and ~20 art students. As we walked from the art presentation to join DW and D2 for the next scheduled event, she casually mentioned while smiling “Well, I won’t be going here.” I gave her shoulder a squeeze and asked how she feels about not going to school with her sister. She simply shrugged and said “It’s probably what I need anyway.”
D1 also received a call yesterday from Moravian to inform her that her portfolio won a $1000 award. The continued positive reinforcement has been good for her confidence, although she’s still rather modest (not necessarily a bad thing). We expect her to make her final decision to become a Greyhound in the next day or two.
Despite the relative shyness of them both, they really are quite self aware. Although I know I’ll worry about them, I’m feeling better about things at this point - due in no small part to the opportunity to document my thoughts here and to the supportive CC community.
@RandyErika Sometimes the more quite students adjust better because they can be comfortable being alone and find things to do. The ones who are used to being surrounded by friends in high school can feel more lonely. More introverted kids come with a toolbox of coping skills.
Once the acceptances are in and the decision is made, all the anxieties about pushing them out of the nest emerge. The majority take to flight quite fine, though can be rough and bumpy at first for everyone. Knowing that doesn’t take the anxiety away, only going through it will (over time). The wild mixture of feelings is all part of the process.
This is April. Your kids will have at least four more months of maturing/growing/developing before they begin college with hundreds/thousands of other freshmen at their schools. They will do fine, just like they made the adjustment to HS.
btw- 3/4 of people are extroverted and society reflects that. However, 3/4 of the highly gifted are introverted. Learned at GT conferences open to parents when kid was in HS. Fortunately introverts most likely don’t really care about the majority and do their own thing (they need their down time, just like extroverts need to be with people some of the time).
No student needs to be in the majority and will likely find their “tribe”, even if they didn’t in HS. They have a lot in common with the other college students at their school- they all chose it.
Don’t make the mistake of comparing the real life, messy human that you’ve lived day-to-day with to that “perfect” classmate you only see at rehearsed recitals or prepared debate competitions. None of us are as polished as our resumes.
It’s normal to be nervous. I certainly was with my eldest. Some of my concerns were unfounded. Some of them I was dead on but underestimated her ability to figure it out when she could and get help when she couldn’t. My son heads off in the fall and I have my own set of concerns for him too but he will also do great. They grow monumentally over those 4 years.
This. My older child chose a college that was within commuting distance but chose to live on-campus. I expected him to ditch the dorms within weeks and decide to commute, and I would have been sorry if that had happened because I think commuting is a far less interesting way to experience college. But it turned out that he loved campus life and took to it easily.
@Lindagaf I need to remember this come September!!