Matthias Adam Shaaber was born on December 13, 1897 in Reading, Pennsylvania to Harry and Emma Shaaber. After graduating from Reading High School in 1914, Shaaber matriculated to the University of Pennsylvania. As an undergraduate, Shaaber was a member of the Phi Gamma Delta fraternity. He earned an A.B. from the University in 1918. After graduation, Shaaber enlisted in the United States Army, where he reached the rank of second lieutenant before being honorably discharged in 1919. Shaaber then took a position at the University of Pennsylvania as an Instructor in English, albeit only briefly as he soon relocated to New York City where he worked for the National Shawmut Corporation from 1920 to 1922.
Shaaber returned to the University of Pennsylvania in 1922, again as an Instructor in English, and earned an A.M. (1924) and a Ph.D. (1929) from the University. He went on to serve as an Assistant Professor of English (1934-37), Associate Professor of English (1937-42), and, finally, Professor of English (1942-68). Shaaber served terms as both the graduate chair and department chair of the English department, and was responsible for enacting a number of changes to the English curriculum. When he retired from teaching in 1968, he was honored as an Emeritus Professor of English. Shaaber was appointed curator of the University's Horace Howard Furness Memorial Library in 1965, a position he kept until his death more than ten years after his retirement from teaching.
A scholar of Shakespeare and English Renaissance literature, Shaaber wrote numerous books and articles on these subjects, continuing to publish prolifically even after his retirement. He was a founding member of the Renaissance English Text Society, the Renaissance Society of America, and the Shakespeare Society of America.
Matthias Adam Shaaber died on December 10, 1979 only three days shy of his 82nd birthday. He was survived by his wife of 46 years, Margaret Donaldson Shaaber.