This chapter deals with the stationary second-order force and moment acting on a floating body in regular waves. Of most interest is the longitudinal force component, the added resistance. The chapter gives a rigorous derivation of the second-order force and moment both in deep and shallow waters, including effects which are usually neglected in the relevant literature. Using a Rankine source potential method, results for the added resistance are computed and compared with results of model experiments and CFD calculations for a sharp and a full ship in deep waters and head waves. Then computed results for the added resistance and the yaw drift moment for various wave directions both in deep and in shallow waters are presented.