The Force Field Toolkit (ffTK), a new plugin for visual molecular dynamics by Christopher G. Mayne et al. on page 2757, aids users in the development of CHARMM/CGenFF-compatible force field parameters for small molecules. The primary function of ffTK is to generate quantum mechanical target data and optimize molecular mechanics force field parameters. The cover shows water interation profiles (center left), which are computed at each iteration of the partial atomic charge optimization, and torsion scans (left to right), which are used to compute potential energy surfaces during dihedral parameter optimization. ffTK also provides a suite of analytical tools to assess optimization metrics and parameter performance using embedded plotting utilities (background).