Abstract Since Richard Pfeiffer first spotted his influenza bacilli in the respiratory secretions of patients suffering from influenza during the Russian pandemic, scientists of all stripes have built, one discovery at a time, a monument to understanding how Haemophilus influenzae, as well as pneumococci and meningococci, cause bacterial meningitis. The culmination of these many, diverse efforts is the near disappearance of this dreadful infection, at least in countries that provide vaccines to their young citizens. Earlier, smallpox, diphtheria, tetanus, whooping cough, measles, and polio became almost nonexistent in America because of a tower of scientific knowledge and the use of vaccines that emerged from that knowledge. Now, meningitis is almost there.