This paper analyzes the behavior of a central bank under strong
("Knightian") uncertainty when the short run trade-off between output and inflation is represented by the Sticky Information Phillips Curve recently proposed by Mankiw and Reis (2002). By solving the robust control problem analytically, this paper elucidates the economic mechanisms at play in a sticky information economy and shows how and why the robust monetary policy in this economy differs from the optimal one identi ed by Ball, Mankiw and Reis (2005).