PyMT is an Open Source Python package, developed by the Community Surface Dynamics Modeling System, that provides the necessary tools used for the coupling of models that expose the Basic Modeling Interface (BMI). It contains, * Tools necessary for coupling models of disparate time and space scales (including grid mappers) * Time-steppers that coordinate the sequencing of coupled models * Exchange of data between BMI-enabled models * Wrappers that automatically load BMI-enabled models into the PyMT framework * Utilities that support open-source interfaces (UGRID, SGRID, CSDMS Standard Names, etc.) * A collection of community-submitted models, written in a variety of programming languages, from a variety of process domains - but all usable from within the Python programming language * A plug-in framework for adding additional BMI-enabled models to the framework