Cream butter and shortening; gradually add sugars, beating well at medium speed of an electric mixer.  Add eggs and vanilla, beating well.  Combine flour, soda, and salt; add to creamed mixture, mixing well.  Stir in chocolate morsels. 

Drop dough by heaping teaspoonfuls onto ungreased cookie sheets.  Bake at 375° for 9 to 11 minutes.  Cool slightly on cookie sheets; remove to wire racks to cool completely.  Yield:  about 6 1/2 dozen.