Heat oven to 325°F.
Cream butter and sugar in medium bowl until creamy. Add vanilla; beat until well mixed.
Add flour and pecans; beat at low speed, scraping bowl occasionally, until well mixed.
Shape dough into 1-inch balls. Place, 1 inch apart, onto ungreased cookie sheets.
Bake 16-18 minutes or until very lightly browned. Cool 5 minutes; roll in powdered sugar while still warm and again when cool.