What is it like in your office when the team gets together in a meeting?  Do some people knock heads?  If you're attempting to brainstorm ideas, do the same people always take center stage in discussions?  Do some people clam up completely?  To get the most from your group you must create a safe environment for discussion, and encourage divergent thinking at the same time! 

Here are some ways to encourage full participation in meetings, while managing to elicit a wide range of ideas.  The death knell for a meeting is "groupthink" wherein creativity withers because the strongest personalities direct the group.

ENCOURAGE DIVERGENT THINKING
People will feel more comfortable to bring up their ideas when you indicate that there are "many ways to look at this topic".  After the most vocal people have verbalized their opinions follow up with, "I want to hear other ideas, other ways to consider the issue.  What are some of the other ideas here?"  Make it clear that you expect and want to hear other opinions.  When the quiet individuals do participate, acknowledge the good points of what they've said.  This encourages more participation. To encourage more ideas, "Okay, we've heard 3 ideas, what other ideas/options are there here?"

You may even give the group "fair warning" at the start of the meeting that you want to hear everyone's opinions, "I want to hear from everyone and we're NOT looking for agreement, but for different ideas.  So I'm going to go around the room to hear what everyone thinks.  We want to hear different opinions and I'm not looking for everyone to agree!"

WATCH FOR BODY LANGUAGE CLUES
Sometimes an individual may have an idea but is hesitant to open his/her mouth.  These individuals often show subtle clues nonverbally, a shift in eyes or posture, a slight opening of the mouth.  Watch for these clues and ask, "Did you have something you'd like to say about this?  Let's hear your thoughts!" 

THE UNSPOKEN THOUGHTS
This is a terrific exercise to get people to open up.  It comes from The Facilitator's Guide to Participatory Decision-Making by Sam Kaner (New Society Publishers, 1996).  This exercise is particularly effective after the group has been discussing an issue that needs to be resolved ... but some people seem to be hesitant to participate. 

THE EXERCISE: 
Have the group break into pairs.  Ask each partner to answer this question: "During this discussion have I had any thoughts that I haven't said aloud?"  This statement may elicit some embarrassed sniggling at first!  Assure people that no one is required to say anything they don't want to say. 

Next ask the pairs to consider this question, "Would the group benefit from hearing your partner's thinking?"  This gives the pairs the opportunity to investigate how to present it to the group.

Now have everyone return to the large group.  Ask for volunteers to share any of their own thoughts that might be useful for others to hear.

NON-JUDGMENTAL BEHAVIORS
A most important element in relation to ensuring a safe environment is modeling non-judgmental behavior.  That is, if you want your team to actively and openly participate in discussion, you must exhibit the words, vocal quality and behaviors that support this message.  Don't interrupt others when they are verbalizing their thoughts.  This is especially important when a person who is typically quiet finally opens up. Give this person space!  Make sure that your voice, your eye contact and your body language show openness to others.  Show others that you listened and ensure comprehension by paraphrasing what you heard, "If I understood correctly, you're saying that ..."  Then give the person the opportunity to confirm or correct the intent.

Also see Boswell's related article: 
Create the Effective "Brainstorm Team"
How do you create a productive environment within which to
investigate new ideas and develop team opportunities?