In a bowl, cream the butter, gradually adding the sugars, eggs, and vanilla. In a separate bowl, mix the flour, baking powder, baking soda, and salt. Stir the dry ingredients into the creamed mixture until uniformly blended. Stir in the oats and raisins. Cover the dough and refrigerate for at least 2 hours.

Preheat oven to 350 degrees F and grease two large cookie sheets. Using mounded tablespoonfuls of dough, make balls of dough almost 2 inches in diameter and lay them onto the sheets, leaving plenty of room for them to spread. Bake for about 22 minutes, or until lightly browned. Cool the cookies on the sheets for 1 to 2 minutes, then transfer to a rack and cool to room temperature.