If you were part of a regiment, orchestra or dance troop in your dream, this suggests a need for more discipline and communicative action in waking life. The people involved may also represent the people with whom you are working in real life. Was everyone in time, marching with purpose or keeping in step? If your dreams take you back to school, college or university reunions, your dream may be suggesting that you are in need of greater intellectual challenge and stimulation in waking life, and that you need to open your mind.
If you were attending a political rally this suggests some anger in your waking life that needs to be worked through.