In a large bowl, cream together the butter, white sugar and brown sugar. Beat in the eggs one at a time then stir in the vanilla. Combine the flour, baking powder, baking soda and salt; stir into the creamed mixture until just blended. Finally, mix in the chocolate chips. Shape dough into golf ball sized balls and place them 3 inches apart into ungreased cookie sheets. Flatten slightly.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.
