The B O S S program performs (a) Monte Carlo (MC) statistical mechanics simulations for solutes in a periodic solvent box, in a solvent cluster, or in a dielectric continuum including the gas phase, and (b) standard energy minimizations, normal mode analysis, and conformational searching. The energetics are represented with the OPLS force fields or the AM1 or PM3 semiempirical MO methods. Besides the quantitative structural and energetic results, other quantities are computed including dipole moments and solvent accessible surface areas that are valuable for many applications such as structure-activity relations.