In medium bowl, combine flour, baking powder and salt; set aside. In large bowl, cream butter, sugars and zest with an electric mixer at medium speed until light and fluffy. Add eggs, one at a time, mixing well after each. Add flour mixture to butter mixture; blend well. Stir in chocolate chips. Drop by tablespoonfuls onto ungreased cookie sheet.
Bake 13-15 minutes, or until edges are golden brown. cool 3 minutes on pan; remove and cool completely on cooling rack.