Andy Rowell has done of nice job of summarizing some of the main theories about church growth. He identifies 14 factors, and what strikes me about this list is how wide-ranging the ideas are. Makes me think that we don't really know what's going on. :-/
"I looked at work from seven researcher teams: Stark, Hout/Greeley/Wilde, Woolever/Bruce, Stetzer/Dodson, Olson, Chaves, and Thumma.
Here is a summary of the 14 factors which I document fully below: (1) witnessing, (2) strictness, (3) high fertility rates, (4) caring for children and youth, (5) high involvement, (6) welcoming new people, (7) leadership, (8) prayer, (9) being a church of 1000+ attendees or under 50 attendees, (10) being located in rural counties, (11) being in rapidly growing zip codes, (12) being in a tradition that is altering worship practices slightly but not too much, (13) churches that offer “intimacy and choice” and (14) attractive worship style, senior pastor, and church reputation."