Ces aro convergence of spherical averages is proven for measure-preserving actions of Markov semigroups and groups. Convergence in the mean is established for functions in L p , 1 ≤ p < ∞, and pointwise convergence for functions in L ∞. In particular, for measure-preserving actions of word hyperbolic groups (in the sense of Gromov) we obtain Ces aro convergence of spherical averages with respect to any symmetric set of generators.