The purpose of this investigation was to propose a method to determine the composition distribution, on one hand, and the molecular weight distribution, on the other hand, for block copolymers. The technique selected to determine this kind of information was Gel Permeation Chromatography, because, since its introduction in 1964, it has become the most powerful tool for the rapid characterization of homopolymers. The proposed method is introduced by considering a dual-approach: composition distribution (calibration of detectors with composition) and molecular weight distribution (calibration of columns with composition). The absence of heterointeractions in block copolymers led to a behavior which depends solely on the elution behavior of the corresponding homopolymers. Finally, it is concluded that all this meaningful information about block copolymers can be perfectly obtained when adequate raw Gel Permeation Chromatography data handling, taking into account composition, is done. / M.S.