Abstract: A method of bringing together and joining plastic cards, which are provided with an identification mark, and printed card carriers associated with the respective plastic cards, has the following steps: providing the plastic card, detecting the identification mark of said plastic card, deriving a test mark from said identification mark of the plastic card in such a way that unequivocal calculating back to the identification mark is not possible on the basis of the test mark, reading a data base by means of said identification mark, printing on the card carrier data read from the data base as well as the test mark, detecting the test mark of the card carrier prior to joining said card carrier to the plastic card, determining whether the test mark derived from the identification mark of the plastic card, which is about to be joined to the card carrier, corresponds to the detected test mark, and, provided that the test marks of the plastic card and of the card carrier correspond, bringing together and joining the