The report presents a method for determining the parameters of ordinary differential equations, where it is not necessary that the equation have a closed-form solution. DIFRED, a computer data-reduction program utilizing the method, is also described. The program is written for an IBM 7090 computer operating under the IBSYS monitor. The mathematical formulation of the method is presented, and the FORTRAN listing of DIFRED and instructions for its use are included. (Author).