Regularity at the Boundary for Solutions of Nonlinear Subelliptic Equations

In this article we establish an estimate, in terms of subel- liptic p-capacity, for the modulus of continuity at the boundary of the solution to the Dirichlet problem associated to a class of subel- liptic quasilinear equations. We infer from it the sufficiency part of a Wiener type criterion for the regularity of boundary points.