1. Preheat oven to 350 degrees F. In medium bowl combine flour, baking powder, baking soda and salt; set aside. In large bowl with mixer at medium speed, beat peanut butter and butter until smooth. Beat in sugars until blended. Beat in eggs and vanilla. Add flour mixture; beat until well blended. If necessary, refrigerate dough.
2. Shape dough into 1-inch balls. Dip in sugar. Place 2 inches apart, sugar side up, on ungreased cookie sheets. Flatten with fork dipped in sugar, making crisscross pattern.
3. Bake 10 minutes or until lightly browned. Remove; cool completely on wire rack. Store in tightly-covered container.