In 3 quart pan, heat to boiling:

   1/2 cup dark brown sugar

   1/2 cup corn syrup

   1/4 cup margerine

Add

   8 cups popped popcorn

and stir until well coated with candy.  Remove from heat and spread on cookie sheet.  Bake in 300° oven for 15 minutes.  Cool 10 minutes and loosen from pan with spatula.  Store at room temperature uncovered.