G-HAT (Growth of Hardwoods After Thinning) is a system of computer programs used to predict growth and yield of Appalachian mixed hardwoods after thinning. Given a tree list or stand table, along with inputs of stand age, site index, and stand basal area before thinning, G-HAT software uses species-specific individual tree equations to predict tree basal area increment and total height for the residual stand. Cubic foot volumes, based on desired merchantability standards, may be obtained for thinned trees, the residual stand, and the projected stand. G-HAT is available as a self-contained, interactive program (BASIC G-HAT) or as a library of FORTRAN subroutines (FORTRAN G-HAT). BASIC G-HAT, for personal computers, is designed for interactive, user-friendly sessions with keyboard input and screen output. Its use requires no programming ability. FORTRAN G-HAT is compatible with mainframe computers, minicomputers, and personal computers. It consists of modular subroutines which allow considerable flexibility in application, such as interface with computerized timber inventory systems and stand simulators.