Abstract: Alerting the population during crisis using available communication systems can significantly reduce the impact of emergency situations. However, the understanding of the alert and trust by recipients is influenced by the alert message content and style. It is therefore desirable that alert messages are formulated with sufficient information and in a style that eases understanding of the message and fosters trust, so that the recommended protective actions are actually undertaken. Within the EU Alert4All project, an alert message dispatcher is being currently implemented, which disseminates alert messages through multiple communication systems in a harmonized manner, fostering best practices in the formulation of alert messages in a user-friendly manner. The design of the dispatcher features and graphical user interface was supported by a field practitioner workshop with participants from different European countries. This paper describes the workshop methodology, its results and the impact on the message dispatcher design.