A multi-application data card is capable of substituting for a plurality of existing single-application data cards. The multi-application data card can be a smart card comprising a memory formed with at least three memory banks or storage areas for storing and updating data relating respectively to at least one authorized holder of the card and at least two authorized applications of the card. Alternatively, the data card can be a conventional card having a magnetic stripe, and the memory functions can be performed at a location remote from the card reader and connected thereto by a data link. In addition, the data card can comprise both a magnetic stripe and solid-state circuitry so that it can be read by a card reader compatible with a magnetic-stripe card or by a card reader compatible with a smart card. In accordance with the invention, a card holder needs to carry just one card for all card uses, both financial and non-financial.