Charles Dexter Allen was an American bibliophile and author, best known for his contributions to the study of bookplates, which are decorative labels affixed to the inside cover of a book to indicate ownership. His most notable work, "American Book-Plates: A Guide to Their Study with Examples," published in 1894, served as a comprehensive resource on the subject, showcasing the artistry and historical significance of bookplates in American culture. Through meticulous research and a keen eye for design, Allen not only cataloged various examples but also provided insights into the artists and engravers behind these unique pieces of art. Allen's work was significant in elevating the appreciation of bookplates as an art form and a reflection of personal identity in book ownership. His dedication to the subject helped to foster a greater understanding of the intersection between literature and visual art in the late 19th and early 20th centuries. Although he may not be widely recognized today, his scholarship laid the groundwork for future studies in the field and contributed to the preservation of this unique aspect of bibliophilic culture. His legacy endures among collectors and scholars who continue to explore the rich history of bookplates and their role in the literary world.