Caramel Popcorn

1 cup or 2 sticks butter or margarine
2 cups firmly packed brown sugar
1/2 cup corn syrup
1 tsp. salt
1/2 tsp baking soda
1 tsp. vanilla
6 qts. popped corn
2 cups peanuts
Melt butter in large sauce pan. Stir in brown sugar, corn syrup and salt. Bring to boil, stirring constantly. Boil without stirring for 5 min. Remove from heat. Stir in baking soda and vanilla. Gradually pour over popped corn and peanuts in 2 large shallow pans. Mix well. Bake in 250 degree oven for 1 hour, stirring every 15 min. Remove from oven and cool completely. Break apart and store in tightly covered container.