We describe an extension of special relativity characterized by three invariant scales, the speed of light, c, a mass, κ and a length R. This is defined by a non-linear extension of the Poincare algerbra, A, which we describe here. For R → ∞, A becomes the Snyder presentation of the κ-Poincare algebra, while for κ → ∞ it becomes the phase space algebra of a particle in deSitter spacetime. We conjecture that the algebra is relavent for the low energy behavior of quantum gravity, with κ taken to be the Planck mass, for the case of a nonzero cosmogical constant Λ = R −2 . We study the modifications of particle motion which follow if the algebra is taken to define the Poisson structure of the phase space of a relativistic particle.