COSMICS is a package of Fortran programs useful for computing transfer functions and microwave background anisotropy for cosmological models, and for generating gaussian random initial conditions for nonlinear structure formation simulations of such models. Four programs are provided: linger_con and linger_syn integrate the linearized equations of general relativity, matter, and radiation in conformal Newtonian and synchronous gauge, respectively; deltat integrates the photon transfer functions computed by the linger codes to produce photon anisotropy power spectra; and grafic tabulates normalized matter power spectra and produces constrained or unconstrained samples of the matter density field.