Pre-heat oven to 350F In a bowl, cream peanut butter, margarine and sugars. Blend in eggs and vanilla.
Add flour sifted with baking powder, soda and salt. Mix well.
Form dough into round balls (about 1 1/2"). Place on ungreased baking sheet. Flatten slightly by criss-crossing with a fork. Tip: dip fork in flour - it won't stick to the batter. Bake at 350°F for 10-12 minutes.