A User-Friendly Fortran BVP Solver L.F. Shampine, Southern Methodist University P.H. Muir and H. Xu, Saint Mary's University MIRKDC is a FORTRAN 77 code widely used to solve boundary value problems (BVPs) for ordinary differential equations (ODEs). A significant issue with this package and similar packages is that the user interfaces are so complicated that potential users may be reluctant to invest the time needed to learn how to use them properly. We have applied our experience in writing user interfaces for ODE solvers in Matlab and Fortran 90/95 to develop a user-friendly Fortran 90/95 BVP solver from MIRKDC. In the course of developing a completely new user interface, we added significantly to the algorithmic capabilities of MIRKDC. In particular, the new solver, BVP_SOLVER, extends the class of BVPs solved by MIRKDC to problems with unknown parameters and problems with ODEs having a singular coefficient. It uses more effective Runge-Kutta formulas and continuous extensions. We have also written a number of auxiliary routines to provide further convenience to users of this package. For instance, there are routines for evaluating the solution and its derivative, routines for saving and retrieving solution information, and a routine that facilitates continuation in the length of the interval.