Summary of the physical bases of the Mintz-Arakawa two-level atmospheric model and presentation of numerical procedures and computer program for its execution. Discussion covers the physics of the model, with particular attention given to the treatment of the moisture and heat sources, including parameterization of convective processes, cloudiness, and radiation. Numerical approximations and finite-difference equations used in the numerical simulations are also given. Throughout the documentation, emphasis is on the specific details of the model in its present form, rather than on derivation or justification of its present design. To facilitate the use of this model, a complete listing of the code as written in FORTRAN language is given, together with a description of all constants and parameters used. Also included are a dictionary of FORTRAN variables and a dictionary of principal physical features. To illustrate the model's performance, samples of its solutions are given for selected variables at a specific time.