Vox in Rama is a decretal sent by Pope Gregory IX in June 1233 condemning the heresy of Luciferianism said to be rife in Germany, and authorizing the preaching of a crusade against it. Copies of the letter were sent to Emperor Frederick II, King Henry (VII) of Germany, Archbishop Siegfried III of Mainz, his suffragans, Bishop Conrad II of Hildesheim and the preacher Konrad von Marburg. The copies are dated to 11, 13 and 14 June.