Use large bowl.

1 (8 oz.) bottle Catalina dressing
1 (8 oz.) bottle Italian dressing (regular, not zesty)
1 bottle Salad Supreme Seasoning (made by McCormick)
1 med. tomato, chopped
1 med. green pepper, chopped
1 med. onion, chopped
1 lb. spaghetti, cooked & chilled

Note: Better if made day before serving.