1. A method for operating an injection valve, the nozzle needle of which is driven by a piezoelectric actuator, characterized in that the dynamic progression of the nozzle-needle stroke is determined and controlled with the following steps: continuous capturing of the ACTUAL quantities constituted by actuator current or actuator charge and/or actuator voltage during an injection process; reconstructing the dynamic progression of the nozzle-needle stroke of an injection valve on the basis of a model structure for a motion of the nozzle needle of an injection valve, and ascertaining the DESIRED quantities constituted by actuator current or actuator charge and/or actuator voltage therefrom, wherein the dynamic progression of the nozzle needle-stroke is reconstructed via a simplified (reduced) model structure by introduction of at least one discrete measured value pertaining to the individual injection valve into a basic model of the nozzle-needle motion; and comparing the DESIRED quantities with the ACTUAL quantities, and minimizing the difference between the two quantities.