The dynamics and control of brachiation robots are analyzed. These robots are underactuated nonlinear mechanical systems whose motion resembles that of a brachiation monkey. Two control methods are proposed to control the three-link robot. One considers only the nonlinear characteristics of the robot, while the other considers both the nonlinear and underactuated characteristics of the robot. Although controllers designed by both methods are able to drive the brachiation robot to the desired position, the motion characteristics and described trajectories are different for both controllers.