Abstract. This paper is concerned with developing accurate and efficient numerical methods for one-dimensional fully nonlinear second order elliptic and parabolic partial differential equations (PDEs). In the paper we present a general framework for constructing high order interior penalty discontinuous Galerkin (IP-DG) methods for approximating viscosity solutions of these fully nonlinear PDEs. In order to capture discontinuities of the second order derivative uxx of the solution u, three independent functions p 1 , p 2 and p 3 are introduced to represent numerical derivatives using various one-sided limits. The proposed DG framework, which is based on a nonstandard mixed formulation of the underlying PDE, embeds a nonlinear problem into a mostly linear system of equations where the nonlinearity has been modified to include multiple values of the second order derivative uxx. The proposed framework extends a companion finite difference framework developed by the authors in [9] and allows for the approximation of fully nonlinear PDEs using high order polynomials and non-uniform meshes. In addition to the nonstandard mixed formulation setting, another main idea is to replace the fully nonlinear differential operator by a numerical operator, which is consistent with the differential operator and satisfies certain monotonicity (called g-monotonicity) properties. To ensure such a g-monotonicity, the crux of the construction is to introduce the numerical moment, which plays a critical role in the proposed DG framework. The g-monotonicity gives the DG methods the ability to select the mathematically "correct" solution (i.e., the viscosity solution) among all possible solutions. Moreover, the g-monotonicity allows for the possible development of more efficient nonlinear solvers as the special nonlinearity of the algebraic systems can be explored to decouple the equations. This paper also presents and analyzes numerical results for several numerical test problems which are used to guage the accuracy and efficiency of the proposed DG methods.Key words. Fully nonlinear PDEs, viscosity solutions, discontinuous Galerkin methods, AMS subject classifications. 65N30, 65M60, 35J60, 35K55, 1. Introduction. Fully nonlinear partial differential equations (PDEs) refer to a class nonlinear PDEs which is nonlinear in the highest order derivatives of the unknown functions in the equations. Due to their strong nonlinearity, this class of PDEs are most difficult to analyze analytically and to approximate numerically. In the mean time, fully nonlinear PDEs arise in many applications such as antenna design, astrophysics, differential geometry, fluid mechanics, image processing, meteorology, mesh generation, optimal control, optimal mass transport, etc [8], which calls for the development of efficient and reliable numerical methods for solving their underlying fully nonlinear PDE problems. This is the second paper in a series [9] which is devoted to developing finite difference (FD) and discontinuous Galerkin (DG) methods for approximating ...