This indispensable handbook explains how scholars and students should work with and think about the composer's working manuscripts. Over the past quarter century, the scholarly study of autograph sources has exploded and nowhere is this more true than in the field of twentieth-century music. And yet, few if any courses or seminars broach the subject of sketch studies and the skills required to examine the manuscripts. This book surveys the knowledge necessary to work efficiently in archives and libraries housing this material and with the skills and techniques specifically related to sketch studies: transcription, reconstructing sketchbooks, deciphering handwriting, dating documents. It deals with the music of important twentieth-century composers and presents visual examples of manuscripts from the collections of world renowned institutions such as the Paul Sacher Foundation. The book aims to make the work of both researchers and students more efficient and rewarding.