The invention concerns a method for making continuous coextruded intermingled glass filaments and continuous thermoplastic organic filaments that enable non-spinnable compounds to be incorporated at the thermoplastic filaments. The invention is characterized in that the thermoplastic filaments are obtained by coextrusion of a thermoplastic material acting as core and a thermoplastic material containing at least one non-spinnable compound. The invention also concerns a device for implementing the method. The resulting composite yarn is provided with specific core properties provided by the non-spinnable compounds.