Cook rice according to package.
Prepare a pot of boiling water.
Cut tops off bell peppers and clean seeds out.
Place in boiling water and cook fro 10-15 minutes, drain.
Brown hamburger meat, drain.
Mix hamburger meat, cooked rice and ¼ cup mozzarella cheese until well blended. Add ½ can of tomato sauce and mix well.
Divide mixture between bells peppers, stuff bell peppers and place in upright position in baking dish.
Pour remaining tomato sauce over top of bell peppers. Top with remaining mozzarella cheese.
Place in pre-heated 350° oven for 25-20 minutes or until heated through and bell peppers are soft.