The Archivo Nacional in Asuncion, Paraguay, is virtually unknown to historians of Latin America in the United States, despite the richness of its holdings on Paraguayan and Platine history. Few North American scholars have used the archive, and there is very little in print, either in English or Spanish, that can acquaint one with what documentation is available. The present writer, despite his efforts to learn as much about the archive as possible before his own extended research visit there in 1968, arrived in Asunción with little idea of what was available, how the archive was organized, or the extent and sheer mass of material awaiting him.