Method in a system for personalizing portable data carriers, the system comprising a personalization data providing unit and a plurality of personalization units (30, 40), the method comprising the following steps: - decrypting personalization data in the data providing unit; - transmitting the personalization data from the providing unit to a first or second of the personalization units (30, 40) - converting personalization data from the system internal format to a first or second application layer format of the first or second personalization unit respectively; - using the converted personalization data for personalizing the portable data carriers in the first or second personalization unit (30, 40); - the data providing unit stores the personalization data in an encrypted form; - the decrypted personalization data are re-encrypted in the data providing unit before being transmitted; - the data providing unit receives a data preparation parameter from the first personalization unit (30, 40); - the data providing unit prepares (306, 307) the personalization data to be transmitted in accordance with the received data preparation parameter; - wherein in the step of preparing only selected data fields of the available data fields in the personalization data are provided for transmission, the data preparation parameter indicating the selection; - in the step of transmitting the personalization data are transmitted in an internal system format, the format being defined in the application layer; - the transmitted, re-encrypted personalization data are correspondingly decrypted in the personalization unit (30, 40) before being converted; and - in the step of converting the transmitted personalisation data are converted. - decrypting personalization data in the data providing unit; - transmitting the personalization data from the providing unit to a first or second of the personalization units (30, 40) - converting personalization data from the system internal format to a first or second application layer format of the first or second personalization unit respectively; - using the converted personalization data for personalizing the portable data carriers in the first or second personalization unit (30, 40); - the data providing unit stores the personalization data in an encrypted form; - the decrypted personalization data are re-encrypted in the data providing unit before being transmitted; - the data providing unit receives a data preparation parameter from the first personalization unit (30, 40); - the data providing unit prepares (306, 307) the personalization data to be transmitted in accordance with the received data preparation parameter; - wherein in the step of preparing only selected data fields of the available data fields in the personalization data are provided for transmission, the data preparation parameter indicating the selection; - in the step of transmitting the personalization data are transmitted in an internal system format, the format being defined in the application layer; - the transmitted, re-encrypted personalization data are correspondingly decrypted in the personalization unit (30, 40) before being converted; and - in the step of converting the transmitted personalisation data are converted.