The posters in this exhibition, about 20 in all by Henri de Toulouse-Lautrec, Alfons Mucha, Jules Chéret, Pierre Bonnard, Felix Vallotton, Paul Berthon and others, document the early history of a thoroughly modern art form. Created in Paris during the Belle Époque—the period including the last decades of the 19th-century and the years leading up to World War I—they had to be simple, dynamic, eye-catching and distinctive.