This is for those who weren't already involved in Bible study. We offered it on Sunday nights for people already connected to a Sunday School class. The attitude of existing members often times closes the door to assimilation because there isn't a spirit of warmth and friendliness and acceptance. Teaching members of existing classes that the purpose of their class is to be an open class so that new comers are always welcomed and creating the climate that makes a newcomer feel welcome will often close the back door of the church. Rather than try to change the personality, we are capitalizing on what they already are and helping them be the best closed leader development groups they can be, while building new, open groups alongside them in the same hour.
New groups are usually easier to keep focused.
Intentional closed groups on Sunday morning during the SS hour. We're also planning on adding additional open groups at other times. Study the needs of your church members. Parents of younger youth, parents of sixth graders, expecting parents, single parents, etc. I would find someone with a passion for one of these groups and mentor them into a teaching team.