This is a collection of 77 Yiddish plays from the Library of Congress:

"The Yiddish theater developed as a uniquely American form in the Eastern European Jewish immigrant community in New York City, and other urban centers, during the early twentieth century. The 77 unpublished manuscripts presented here include light comedies and dramas, and have been selected from the more than 1,290 copyright-deposit plays known as the Marwick Collection and housed in the Hebraic Section of the African and Middle Eastern Division."

Download: Zachary M. Baker, The Lawrence Marwick Collection of Copyrighted Yiddish Plays at The Library of Congress: An Annotated Bibliography (Library of Congress Washington, D.C. – 2004).