Oven at 200 degrees for 1 hour.

2 lg. bowls popcorn (air popped)
1 c. butter
2 c. brown sugar (light)
1/2 c. light Karo syrup
1 tsp. vanilla
1 tsp. baking soda

Melt butter. Stir in sugar and Karo. Bring to boil under low heat. Stir constantly. Turn to low heat and let boil for 5 minutes. Without stirring. Remove from heat and stir in vanilla and baking soda.

Pour over popcorn and mix well. Turn into greased pan with sides. Bake for 1 hour stirring every 15 minutes. Spread onto wax paper and let cool. Store in airtight containers.