Social group for 9-year old boy, ideally Oakland

I'm looking for a social group for my 9-year old son, ideally in Oakland. He's an only child, LIVES to be around other kids, and has some social skills gaps that make friendships harder for him. The group could be professional (facilitated) or informal (families with similar kids getting together). If you have a referral or would like to chat about getting similar kids together, I'd love to hear from you!