This chapter discusses the critical foundations of Pirandello studies, covering Pirandello’s own literary criticism and theorizations of his work, his contemporaries’ assessments, and the central ideas in Pirandello studies put forth by a variety of specialists in Italian literature and theatre studies. Special attention is given to the pioneering critic Giacomo Debenedetti and his conception of the author’s output as a perpetual work-in-progress. Other key figures mentioned include Peter Szondi, Leonardo Sciascia, Giancarlo Mazzacurati, and Giovanni Macchia, as well as Claudio Vicentini, Robert Brustein, and Eric Bentley.