Preheat oven to 350 degrees F (175 degrees C). Grease baking sheets. Sift together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream together the butter, white sugar, and brown sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Gradually stir in the sifted ingredients. Stir in the rolled oats and chocolate chips. Drop by rounded teaspoonfuls onto the prepared baking sheets.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheets for 5 minutes before removing.