Stir boiling water into dry jello mix in medium bowl for at least 2 minutes until completely dissolved. Add whipped topping to hot jello, stir with wire whisk until whipped topping is completely melted and mixture is well blended. Mixture will be thin.
Pour into 10 glasses or 6 cup mold or glass bowl sprayed with cooking spray.
Refrigerate 8 hours or overnight, if using a large mold, unmold onto serving plate just before serving.