There are two things I have found really helpful with group work in an ESL classroom:

1. When I had planned group work or activity as a part of the lesson, I kept creating chaotic situations. My problem: I arranged the groups, then gave the instructions for what to do. By the time the groups were formed, I had lost the control. I ended up having to go from group to group to explain what we were doing. This may be a trivial point to experienced teachers, but I learned that I must give all the instructions and demonstrate the activity BEFORE I'd have the students go into groups.

2. To have the class come back together from the group took sometimes 5+ minutes. Regrouping as a class was an exercise in futility. Then I realized that putting the group work to the end of the class would be more successful, because there would be nothing else scheduled for the class. It works.