Statistical information on the Russian Social Democratic Labor Party is notably scarce. Like any illegal underground party, the RSDRP had neither the means nor the opportunity to record at regular intervals the size, age, profession, sex, and class of its membership. About the best it could do was to pass out a questionnaire at its infrequent congresses in an attempt to solicit the vitae of the party hierarchy if not of the rank and file in the underground. But even this information is lacking for the important ten-year interval between the Fifth Party Congress of 1907 and the Sixth Congress held in Petrograd during the revolution. Historians seeking statistical material on prerevolutionary Social Democracy can, of course, turn to the biographic compilations made by early Soviet historians or to the profiles drawn from agents' reports by the Okhrana.' The former, however, are highly selective and incomplete, and the latter are of questionable accuracy. Another interesting but relatively unknown source of statistical information on the underground party is a questionnaire that Leon Trotsky circulated in 1910. Trotsky announced in April 1910 that he planned to take a "census" "to ascertain the actual condition of our party, the mood of the working masses," and especially "the strengths and resources of the party at the local level."2 Questionnaires were to be obtained free of charge by members of all Social Democratic factions through the distribution network of his emigre newspaper, Pravda. Like many a would-be bellaviorist, Trotsky complained that his subjects were slow in answering, that they gave incomplete answers, or that they found excuses for simply not replying. By the end of January 1911 he had received some ninety-two responses from twenty-seven cities in Imperial Russia, which he partially tabulated, excerpted, and published in three issues of Pravda.3 This data pertained to the profession of party members, their age,