Our adult Bible fellowships are organized into care groups that consist of five to seven family units (you can learn more about the care groups here). Our church recently had a care group fellowship night, and God used it in a mighty way.
The event consists of every care group from every adult Bible fellowship gathering in the home of the care group leader. After a slightly abbreviated Sunday evening service, we encouraged every care group leader to have their care group over to their home for food, fellowship, and testimonies.
The church provided childcare for infant through teens which provided a great opportunity for children and teen ministry activities.
The church helped promote this event, and every adult Bible fellowship teacher made sure everyone from their class had a home to go to. The church provided the flatware and utensils, and the individual home fellowships were encouraged to provide the refreshments or do something potluck style.
At the fellowship, we encouraged the care group leader to open the evening in prayer, and then begin serving the food and encouraging fellowship. We also encouraged some testimonies, and with this event being so close to Thanksgiving, it was natural for people to share what they were thankful for.
My wife and I hosted a care group fellowship for our class and ended up having our entire class over. We had every couple introduce each other: the husband had to introduce his wife, tell us how long they had been married, and something about her that he loved; the wife had to introduce her husband, tell us how long they had been in the class/church, and something she admired about her husband. This worked really well!
The average group took between one-and-a-half to two hours for this event and then sent everyone back to the church to pick up their children. Some of our more mature adult classes did their fellowships in the afternoon to make it easier for some of our elderly.
This time of fellowship helps strengthen the class and bond the class members closer to each other, which, in turn, strengthens the church. I would certainly encourage every church to consider doing this in the New Year.