The book presents a study and the most complete edition of the texts of acts and documents of the Galicia-Volyn principality. It contains original and copy authentic acts and documents, reconstructed acts from annals and chroniclers, documents dubious about reliability, as well as documents of the then and later centuries, which mention known and still unknown documents of the principality. 227 acts and documents were processed. Published documentary materials are different in content and diplomatic form, published by all sorts of persons and institutions in different places.