S2SIMSAP and SlMTlM are computer programs that have been developed to simulate the stand growth and development of natural and treated even-aged northern hardwood stands. SIMSAP begins with species distributions by quality classes in sapling stands after regeneration. SIMTIM, the poletimber-sawtimber-harvest phase, uses stocking guides based on quadratic mean stand diameter, number of trees, and basal area per acre of trees in the main crown canopy. Using available data, the connecting phases of the models have been tebted to determine the effects of silvicultural treatments (or no treatment) on long-term stand response. The models are coded in FORTRAN 77 and are available on mainframe and IBM compatible microcomputers with a minimum of 256 K.S3.