Did trouveres and troubadours write their secular songs in the vernacular?

Yes, trouvères and troubadours wrote their secular songs in the vernacular languages of their regions. Troubadours, primarily from the Occitan-speaking regions of southern France, composed in Old Occitan, while trouvères, from the northern regions, wrote in Old French. This use of vernacular language made their poetry and songs more accessible to the general populace, reflecting the cultural and social themes of their time.