Summary. The object of this paper is the numerical solution of nonlinear two-point boundary value problems by Newton's method applied to the discretized problem on successively refined grids. The first part consists of a theoretical development of a phenomenon that often occurs in practice, namely, that the number of iterations for Newton's method to converge to within a fixed tolerance and for a fixed starting vector is essentially independent of the mesh size. The second part develops a process based on these results for determining an efficient mesh refinement strategy. Numerical results are also provided. This paper deals with the numerical solution of nonlinear two-point boundary value problems by Newton's method applied to the discretized problem on successively refined grids. One aim is to give a rigorous demonstration for a phenomenon which has frequently been observed in computation, viz. that the number of iterations for Newton's method to converge to within a fixed tolerance and for a fixed starting value is essentially independent of the mesh size. Several theorems having rather complex developments are established in Sections 2 and 3, culminating with the establishment of independence of the number of Newton iterations from the mesh size. In the last section, we use this result as a basis for an efficient mesh refinement strategy. The idea here is that if the discrete problem under consideration is to have ultimately a large number, N, of equally spaced grid points, then the process should begin with a coarse grid of, say, No points. After the Newton iterates have converged to within a prescribed tolerance, the grid is to be refined by a factor p, interpolating the last iterate to the new grid and using this as a new starting value for the Newton