The Serenata con una Cantatina by Ignaz von Seyfried is a particular work for choir, soloists and Harmoniemusik, which was performed in 1805 for a courtly occasion. The music is above all entertaining, but certain objectives, probably imposed by Empress Maria Theresia, are in the background. The objective is to understand how Seyfried combines a festive but cultivated music with social and political purposes. The origins of the score and the creation process are first considered. The issues at stake are exemplified by an analysis of the different movements, particularly the Quolibet. This study aims to reveal the composer's engagement, the performance practice as well as the reception of this work a time when the Harmoniemusik was very successful in Vienna.