In a bowl, combine the flour, baking powder, baking soda, and salt; cut in shortening until the mixture resembles coarse crumbs.

Stir in buttermilk; knead dough gently. Roll out to 1/2 inch thickness.

Cut with a 2 and 1/2 inch biscuit cutter and place on a lightly-greased baking sheet.

Bake at 450 degrees for 10-15 minutes or until golden brown.