MESQUITE is a linkable software library that applies a variety of node-movement algorithms to improve the quality and/or adapt a given mesh. Mesquite uses advanced smoothing and optimization to: Untangle meshes, Provide local size control, Improve angles, orthogonality, and skew, Increase minimum edge-lengths for increased time-steps, Improve mesh smoothness, Perform anisotropic smoothing, Improve surface meshes, adapt to surface curvature, Improve hybrid meshes (including pyramids & wedges), Smooth meshes with hanging nodes, Maintain quality of moving and/or deforming meshes, Perform ALE rezoning, Improve mesh quality on and near boundaries, Improve transitions across internal boundaries, Align meshes with vector fields, and R-adapt meshes to solutions using error estimates. Mesquite improves surface or volume meshes which are structured, unstructured, hybrid, or non-comformal. A variety of element types are permitted. Mesquite is designed to be as efficient as possible so that large meshes can be improved.