We had an excellent experience with PEERs, but I would only recommend it for kids who need to work on the skills they cover (mostly around reciprocal conversation).

Outschool has some small group classes.

NP, anybody know of any online resources or books?

Following - for bright DD with ADHD/ mild dyslexia with anxiety but rather narcissistic (maybe most teens are?)

You need to give WAY more information. At this age there are so many different levels and types of social issues. In some cases it's just about finding the right after school activities and getting some extra coaching. Some kids need a group with direct teaching. Some factors that play in:

Is there a diagnosis such as ADHD, ASD, Anxiety disorder?
Level of cognitive functioning?
Does tween/teen have any friends? if so, is the issue of not enough friends/easily taken advantage of/mean girl/easy target/shyness?
Does the child appropriately greet people or does the kid not even say hello to people?
Is there any physical and social aggression?
Any behavioral issues?

Any recommendations?