The present study describes a significant step in this direction, the optimization of a small molecule force field using an automated and reproducible procedure, with all software, data, and workflows made freely available to the maximum extent possible. The result, OpenFF 1.0.0, code-named Parsley, is the first optimized force field using the SMIRNOFF format, with direct chemical perception. To create Parsley, we started with an initial force field called SMIRNOFF99Frosst consisting of direct chemical perception typing rules and parameters adopted from the Parm@Frosst force field. We then optimized nearly all 500 of the valence parameters to improve agreement with quantum chemical optimized geometries, energetics, and vibrational frequencies, while largely retaining the Lennard-Jones and electrostatic parameters of SMIRNOFF99Frosst. In keeping with the Open Force Field Initiative's core philosophy, the Parsley force field and the software tools and data sets used to develop it are released under permissive open source licenses.