MPQC is the Massively Parallel Quantum Chemistry Program. It computes properties of atoms and molecules from first principles using the time independent Schroedinger equation. It runs on a wide range of architectures ranging from single many-core computers to massively parallel computers. Its design is object oriented, using the C++ programming language. Capabilities * Closed shell, unrestricted and general restricted open shell Hartree-Fock energies and gradients * Closed shell, unrestricted and general restricted open shell density functional theory energies and gradients * Second order open shell perturbation theory (OPT2[2]) and Z-averaged perturbation theory (ZAPT2) energies. * Second order closed shell Moller-Plesset perturbation theory energies and gradients. * Second order Moller-Plesset perturbation theory including an R12/F12 correlation factor. Energies of closed- and open-shell systems are supported. * Explicitly-correlated R12/F12 coupled-cluster methods via interface to Psi3 code and via native (experimental) implementation. * Explicitly-correlated multireference methods (MRCI, CASPT2) via interfaces to GAMESS and MOLCAS codes. * Robust internal coordinate geometry optimizer that efficiently optimizes molecules with many degrees of freedom. Nearly arbitrary internal coordinate constraints can be handled.