Mentor based small groups require a lot more dedication and reliability from their group members, but the payoff can be increased growth and community. 

A mentor based group usually pairs a mentor with one or more mentees in a small group setting that opens up the lines of communication for people to ask questions, grow, learn from the mistakes of others, and create accountability.  Here are a few ideas on how these groups could look:

Mothers/Fathers groups:  An older, more experienced mom with grown kids can mentor moms of younger kids.  A group of younger moms can support each other and learn from the mentor mom.

Parent groups:  Like the mother or father group, but with couples instead of just one parent.

College/Career:  A lot of college small groups already have the makeup of a mentorship group but without the title or direction.  When the group is called a mentor group, it can create more of an atmosphere of learning life lessons.