cg_pyrosetta is implemented as a Python package that adds new CG functionality to PyRosetta, and can be found at https //github.com/shirtsgroup/cg_pyrosetta. This functionality is added using a set of CG residues, CG atomtypes and CG movers. These additions to PyRosetta work natively in PyRosetta/Rosetta objects and allow for the design and folding of CG models. Natively, PyRosetta creates immutable library objects once data files are read, therefore external data files must be loaded when PyRosetta initializes.