Abstract: A method of labeling product packages on a thermoforming packaging machine is provided to prevent the unnecessary dispensing of labels onto unfilled, improperly filled and absent product packages. Crosswise rows of product packages are moved in a downstream transport direction on the thermoforming machine using alternating dwell and advancing intervals. A labeling device mounted on the thermoforming packaging machine moves back and forth between a downstream position and an upstream position and applies to the product packages while the labeling device is moving from the downstream position to the upstream position and while the labeling device is moving from the upstream position to the downstream position.