Recipe for 18-20 people:

32 c. bread cubes (about three 16 oz. loaves)
8 c. diced celery
1 1/2 c. onion, diced
1 1/2 tbsp. salt
1 tsp. pepper
Amount of liquid-broth would vary with desired moisture

Following amounts are for reduced quantities (listed in same order as above) : 16 cups, 4 cups 3/4 cup, 3/4 tablespoon, 1/2 teaspoon; 12 cups, 3 cups, 2/3 cup, 1 1/4 teaspoons, 1/4 teaspoon; 4 cups, 1 cup, 1/4 cup, 3/8 teaspoon, 1/8 teaspoon.