The article provides an overview of the IMPACT molecular mechanics program, emphasizing recent developments and its current functionality. It covers core molecular mechanics technologies, including fixed charge and polarizable force fields, and describes how these force fields, combined with new atom typing and parameter assignment modules, have expanded the coverage of organic compounds and medicinally relevant ligands. The program includes advanced conformational sampling algorithms and specialized modules such as Glide (a high-throughput docking program) and QSite (a mixed quantum mechanics/molecular mechanics module). The article also discusses the integration of IMPACT with the Maestro graphical user interface, which simplifies system preparation, job execution, and analysis. Additionally, it details the development of the OPLS_2003 force field for proteins and the polarizable force field for pharmaceutically relevant organic molecules, highlighting improvements in accuracy and coverage. The article concludes with a discussion on solvation models and the Fast Multipole Method for treating long-range electrostatic interactions.The article provides an overview of the IMPACT molecular mechanics program, emphasizing recent developments and its current functionality. It covers core molecular mechanics technologies, including fixed charge and polarizable force fields, and describes how these force fields, combined with new atom typing and parameter assignment modules, have expanded the coverage of organic compounds and medicinally relevant ligands. The program includes advanced conformational sampling algorithms and specialized modules such as Glide (a high-throughput docking program) and QSite (a mixed quantum mechanics/molecular mechanics module). The article also discusses the integration of IMPACT with the Maestro graphical user interface, which simplifies system preparation, job execution, and analysis. Additionally, it details the development of the OPLS_2003 force field for proteins and the polarizable force field for pharmaceutically relevant organic molecules, highlighting improvements in accuracy and coverage. The article concludes with a discussion on solvation models and the Fast Multipole Method for treating long-range electrostatic interactions.