A theory of controlling contact is presented based solely on sensory information about the rho functions of changing gaps and the animal's orientation to gravity. The rho function of a gap is the relative rate of change of size of the gap and is directly available in all sensory modalities, unlike size and rate-of-change of size, which require scaling information. The rhos involved in contacting a moving object are the rho of the distance gap between the animal and the object, the rho of the angular gap between the animal's direction of movement and the direction of the object, and the rho of the vertical gap between the object and the horizontal plane through the animal. Movement to contact is controlled by pair-wise coupling these rhos, i.e., keeping the ratios between rhos constant. The values of the ratios determine whether contact will be gentle or forceful, i.e., achieved with zero or non-zero linear or angular momentum. The theory is applied to explaining sensory guidance of movement to catch a high ball.