Complex Instruction (Cohen & Lotan, 1997) is a variation on cooperative learning that has been more successful because it directly addresses issues of status and access.

• Tasks need to be group-worthy, draw on multiple abilities, and have multiple entry-points.
• Students need to know and have practiced the collaborative norms, particularly roles that they take on within the group.
• Teachers need to stress the importance of multiple abilities in doing mathematics.
• Teachers need to look for times in which certain students are not being listened to in their groups, and at that point do a status intervention with them: a specific, relevant public comment that assigns competence to that student.

Here is Jo Boaler (math education professor at Stanford University) explaining Complex Instruction. Also on that page there is a research article she wrote about the successful use of the approach in a high school.

I particularly like this new book on using Complex Instruction with elementary school students.  Great book, super readable, and right on the money.