The Vita tripartita Sancti Patricii is a bilingual hagiography of Saint Patrick, written partly in Irish and partly in Latin. The text is difficult to date. Kathleen Mulchrone had assigned a late ninth century date based on the latest historical reference in the text. However, on linguistic grounds, it has been dated to as late as the twelfth century. The text as it stands probably reflects various stages of development. Máire Herbert summarises:While there are some textual references indicative of ninth-century date, in my opinion the text was continued thereafter and completed around or after the mid-tenth century. Some decades later, in the eleventh century, the text was edited as a tripartite homily designed for preaching during celebration of the saint's feast.