This is a very general question. Can you please give us a little more information?
How old are your students?
Is it that they aren't listening to directions or each other?
What kind of rules do you have in place?
Do your students listen to anyone?
Is the problem more apparent at a certain time like after lunch?
Do the listen during one subject better than another?
What do you do when they aren't listening?
The more information you cangive us, the better the advice we can give you. I am better at dealing with elementary problems, so please feel free to email me directly if you'd like.