Abstract.A nonholonomic system, for short "NH,'' consists of a configuration space Q n , a Lagrangian L(q,q, t), a nonintegrable constraint distribution H ⊂ T Q, with dynamics governed by Lagrange-d'Alembert's principle. We present here two studies, both using adapted moving frames. In the first we explore the affine connection viewpoint. For natural Lagrangians L = T −V , where we take V = 0 for simplicity, NH-trajectories are geodesics of a (nonmetric) connection ∇ NH which mimics Levi-Civita's. Local geometric invariants are obtained by Cartan's method of equivalence.As an example, we analyze Engel's (2-4) distribution. This is the first such study for a distribution that is not strongly nonholonomic. In the second part we study * The authors thank the Brazilian funding agencies CNPq and