The simplest form of facilitation entails ensuring that all involved have a chance to speak and that the meeting starts and ends on time. Any group member can do this, especially if the group agrees to support them at it. (It can help to rotate the responsibility, giving all group members a turn at it. Participants rapidly come to appreciate what a creative challenge facilitiation is - it is simple, but not necessarily easy. Everyone is then more respectful when their peers try to play the role.) Alternatively an experienced facilitator can be brought in. This is especially necessary during a one-time event, or with people who don't know each other, or with a group that hasn't had good success facilitating themselves. Finally, the role can be held by one or a few group members who develop special skills in it - or even, in a mature, Consensus Process-oriented group, shared by all group members equally all the time (i.e., no one is "the facilitator" but the functions of faciltation are carried out by any and all participants in a fluid way as the meeting proceeds).
Good facilitators always explain their approach and get some agreement from the group as to what is going to happen. In a regularly-meeting group, this may just involve getting agreement on the agenda. Some facilitators discuss broad dialogue guidelines with participants and get them to agree to try applying them. Often such guidelines are posted on a wall where they can be referred to during the dialogue.
The facilitator says that he or she will be trying to shepherd the conversation along the guidelines described. Then the facilitator lets people talk, giving them gentle reminders as necessary.
Of course, to the extent all participants are brief, mindful, and curious about what each other has to say, little formal facilitation or gimmicks are necessary to ensure healthy dialogue.
Many facilitators give special attention to ensuring everyone feels well heard. They may also write important points that come up on chart pads in front of the room.
There are many approaches to facilitation, and many methods on this NCDD Wiki list have their own associated facilitation styles, professional networks and trainings.
Facilitation 101 by Edward S. (Ned) Ruete - http://www.iaf-world.org/about/facil/ReuteFac101.cfm
What is facilitation? by Lisa Heft - http://www.openingspace.net/facilitation_facilitation.shtml
Facilitators Guide to Participatory Decision-Making by Sam Kaner, et al. (New Society, 1996) - a very understandable guide to facilitated Consensus Process, organized so that pieces can be copied and used by the group. Includes an interesting model of group process.
Facilitation Points by Tree Bressen (consensus) - http://www.treegroup.info/toolbox/B11-facilitation_points.html
Institute for Cultural Affairs (ICA). ICA/Chicago, 4750 N. Sheridan Rd., Chicago, IL 60640; 312-769-6393. Offers facilitation and group process trainings in U.S. cities and internationally. http://www.icaworld.org/.
International Association of Facilitators (IAF). 7630 W. 145th St., Suite 202, St. Paul, MN 55124; 612-891-3541; firstname.lastname@example.org; http://www.iaf-world.org. Sponsors an annual conference, publishes a journal.
[What Is Facilitation][http://www.openingspace.net/facilitation_facilitation_defintions.shtml] - a brief description for those new to the term, by Lisa Heft