IN A LARGE BOWL COMBINE ORANGE JELL-O AND BOILING WATER.
WHISK UNTIL JELL-O IS DISSOLVED.
ADD COLD WATER AND ALLOW TO CHILL FOR 15 MINUTES IN REFRIGERATOR.
SLOWLY WHISK IN VANILLA PUDDING MIX UNTIL SMOOTH AND CHILL FOR ANOTHER 15-20 MINUTES OR UNTIL IT BECOMES SLIGHTLY THICKENED.
FOLD IN COOL WHIP, MANDARIN ORANGES AND MARSHMALLOWS