The effect on trailer stability of hitchpoint lateral stiffness and damping is examined by means of a simplified model. The model used in the stability analysis is a one degree of freedom nonholonomic dynamical system and yields a third order linear differential equation. Trailer stability criteria are developed, and stability charts are presented which depict the stability criteria in terms of nondimensional parameters. The analysis shows that increasing hitchpoint lateral stiffness does not improve trailer stability whereas increasing hitchpoint lateral damping is much more important to trailer stability. In addition, the importance of hitchpoint loading to trailer stability is shown.