A method of personalizing identification cards having erasable and/or overwritable and non-overwritable data. The neutral identification cards, before being written on, are first fed from an input stack to a unit in which the overwritable storage medium, e.g. a magnetic stripe, is written on with the erasable or overwritable data. After the writing process has been checked, the card is removed from the process if its writing is defective, and possibly reinserted in the input stack. If the writing is in order, however, the card is fed to another unit in which it is provided with the non-erasable or non-overwritable data.Data records are made available by a card-issuing agency in order to personalize the identification cards. One data record is kept on hand in a buffer memory for the writing of each identification card. The buffer memory is only loaded with a new data record after the correct writing on the magnetic stripe has been signalled, while the part of the old data record necessary for writing on the non-overwritable data is transferred to a second memory. A data record is thus only assigned permanently to an identification card when the technically delicate processing steps have been successfully carried out. In this way the reject rate can be kept low at a high throughput. The produced cards are also stacked automatically in the same order as the delivered data records.