The Thirties were the heyday of the Communist Party only in the sense that the environment was most favorable then--and the fact that the party was little more than a sideshow in American politics signifies that its heyday was really its period of greatest defeat. Following the model of Theodore Draper's classic Roots of American Communism and Maurice Isserman's recent account of the war years (Which Side Were You On?, 1982), Emory U. political scientist Klehr fills in the details on the period's doctrinal struggles, organizing efforts, and other staples of Communist Party history. Steeped in interview sources and in original documents (many collected by Draper for an unfinished book on the period), Klehr's text is very well informed and informative. With government repression in abeyance, anti-Soviet feelings at a low point, and the economy in a shambles, the Communists stood to benefit; but their efforts were sometimes incoherent and always divisive. They look a sad lot altogether: participating in elections while ridiculing electoral politics; organizing marches of the unemployed while failing to provide an ongoing organization for them; running editorials denouncing Socialist Party leader Norman Thomas while ignoring the stockmarket crash the next day. The party's leadership ranks were thin, Klehr observes--so the few effective leaders were constantly being shuffled around, leaving another hole behind. Distrustful of intellectuals, the Communists attracted some creative fellow-travelers (John Dos Passos, Malcolm Cowley, Theodore Dreiser); more typically, they deterred literary figures with a steady stream of invective--more interested in preaching the virtues of proletarian artists than in developing them. Much more time was spent tracking down suspected Trotskyists or plotting factional struggles between the followers of Earl Browder and William Z. Foster--strnggles all the more confusing because of the zigzag course of directives from Moscow. In 1935, after electoral victories by non-communist populist parties in Wisconsin and Louisiana, and strong populist showings in California and Minnesota, party leader Browder got Comintern permission to create a new labor party to expose its left competitors as class traitors and the Democrats as crypto-fascist. By the end of the 1935 presidential campaign, however, the party was staunchly defending Roosevelt and the New Deal--on orders from Moscow. Browder himself ran for president in 1936 and indirectly supported Roosevelt, a deft performance that won him some recognition and swung left votes to FDR. This new united front policy brought gains in union organizing (primarily in the CIO) and some political respectability. Party membership grew until the end of the decade--when Stalin and Hitler signed their famous pact. Klehr follows the twists and turns without attempting a lot of interpretation, and the result is a straightforward, complete account. Well researched and well executed--and intrinsically important.