Scorned by critics since birth, decreed dead by many, naturalism, according to Donald Pizer, is “one of the most persistent and vital strains in American fiction, perhaps the only modern literary form in America that has been both popular and significant.”   To define naturalism and explain its tena­cious hold throughout the twentieth century on the American creative imagination, Pizer explores six novels: James T. Farrell’s Studs Lonigan, John Dos Passos’s U.S.A., John Stein­beck’s The Grapes of Wrath, Norman Mailer’s The Naked and the Dead, William Styron’s Lie Down in Darkness, and Saul Bellow’s The Adven­tures of Augie March.   Pizer’s approach to these novels is empiri­cal; he does not wrench each novel awk­wardly until it fits his framework of general­izations and principles; rather, he approaches the novels as fiction and arrives at his defini­tion through his close reading of the works.   Establishing the background of natural­ism, Pizer explains that it comes under attack because it is “sordid and sensational in sub­ject matter,” it challenges “man’s faith in his innate moral sense and thus his responsibility for his actions,” and it is so full of “social documentation” that it is often dismissed as little more than a photographic record of a life or an era; thus the “aesthetic valid­ity of the naturalistic novel has often been questioned.”   Pizer posits the 1890s, the 1930s, and the late 1940s as the decades when naturalism flourished in America. He concentrates on literary criticism, not on the philosophy of naturalism, to show that literary criticism can make a contribution to a particularly muddled area of literary history—a natural­ism that is alive and changing, thus resisting the neat definitions reserved for the dead.