2 (4.5 ounce) cans Swanson(r) Premium Chunk Chicken Breast in Water, drained
1/4 cup chopped celery
1 tablespoon finely chopped onion
2 tablespoons nonfat mayonnaise
2 tablespoons nonfat plain yogurt
1/8 teaspoon ground black pepper
8 slices Pepperidge Farm(r) Whole Grain 100% Whole Wheat Bread
4 tomato slices
4 lettuce leaves