MOLPOP-CEP calculates the exact solution of radiative transfer problems in multi-level atomic systems. The radiative transfer equations are analytically integrated to reduce the final problem to the solution of a non-linear algebraic system of equations in the level populations. The code uses Coupled Escape Probability formalism to analytically solve the radiative transfer. Written in Fortran 90, MOLPOP-CEP is limited to plane-parallel slabs that can present arbitrary spatial variations of the physical conditions.