Heat oven to 325°F. Heat taco shells as directed on box.
Meanwhile, if chicken is cold, place in medium microwavable bowl; microwave on High 1 to 2 minutes or until hot. Stir in 1/2 cup of the dressing to coat.
Spoon warm chicken mixture into warm taco shells. Top with lettuce, tomato, cheese, onions and olives. Drizzle or serve with remaining dressing.