Ergo is a quantum chemistry program for large-scale self-consistent field calculations. Key features of the Ergo program: * Performs electronic structure calculations using Hartree-Fock and Kohn-Sham density functional theory. * Written in C++. * Uses Gaussian basis sets. * Both core and valence electrons are included in the calculations. * Both restricted and unrestricted models are implemented for energy calculations. * Implements a broad range of both pure and hybrid Kohn-Sham density functionals. * Employs modern linear scaling techniques like fast multipole methods, hierarchic sparse matrix algebra, density matrix purification, and efficient integral screening. * Linear scaling is achieved not only in terms of CPU usage but also memory utilization. * The time consuming parts of the code are currently parallelized using the shared-memory paradigm. WWW: http://www.ergoscf.org/