The extraordinary proliferation of political demonstrations around the world over the past several years has reminded us once again of the phenomenal power of the real-time convergence of people in public space, a power to which Diego Rivera's Moscow Sketchbook—a corpus of forty-five small watercolor drawings—bears graphic witness. The sketchbook dates from Rivera's seven- or eight-month sojourn in Moscow, which began in early November 1927 with his direct participation in the celebration of the tenth anniversary of the revolution as a delegate to the inaugural internat ional Congress of Friends. Publicly announcing the artist's arrival in Moscow on November 3, the Communist Party's national daily newspaper Pravda discussed his “extraordinary frescoes” in the new Secretar iat of Public Educat ion in Mexico City—which the poet Vladimir Mayakovski had earlier lauded as “the world's first Communist mural”—and went on to explain that, as a revolutionary artist, Rivera now prefers the collective address of “wall painting” over the private easel picture to which he had devoted himself for a decade or so in Paris before 1921. A new venture in Soviet cultural diplomacy, the Congress of Friends had as its objective the forging of a broad, cross-party international alliance of those willing and able to come to the defense of the Soviet Union in their home countries. Rivera, a member of the Mexican Communist Party at the time, participated in the congress at the invitation of the Comintern, which was responsible for hosting notable foreign communists when they were in town and, as such, played a major role in the organization of the three-day meeting. On the first day of the congress the artist was elected—from a pool of 947 delegates—to its Presidium (governing board) and press bureau as a member of the foreign intelligentsia.