The article by Goldschneider, Gotschlich, and Artenstein explores the role of humoral antibodies in human immunity to *Neisseria meningitidis*. They argue that the occurrence of meningococcal disease is more related to individual susceptibility than to the virulence of the organism. Epidemiological findings suggest that individuals susceptible to systemic meningococcal disease lack humoral antibodies to meningococci. The authors present evidence that serum bactericidal activity against meningococci is inversely proportional to the incidence of meningococcal meningitis in the general population. They also report that baseline sera from cases of meningococcal disease lack bactericidal activity against homologous and heterologous strains of meningococci, confirming the absence of antimeningococcal antibodies. However, these individuals can respond immunologically to infection, as evidenced by the increased levels of IgG, IgM, and IgA antibodies in convalescent sera. The study concludes that susceptibility to systemic meningococcal disease is related to a selective deficiency of humoral antibodies to pathogenic strains of meningococci, and that exposure to these organisms is crucial for developing immunity.The article by Goldschneider, Gotschlich, and Artenstein explores the role of humoral antibodies in human immunity to *Neisseria meningitidis*. They argue that the occurrence of meningococcal disease is more related to individual susceptibility than to the virulence of the organism. Epidemiological findings suggest that individuals susceptible to systemic meningococcal disease lack humoral antibodies to meningococci. The authors present evidence that serum bactericidal activity against meningococci is inversely proportional to the incidence of meningococcal meningitis in the general population. They also report that baseline sera from cases of meningococcal disease lack bactericidal activity against homologous and heterologous strains of meningococci, confirming the absence of antimeningococcal antibodies. However, these individuals can respond immunologically to infection, as evidenced by the increased levels of IgG, IgM, and IgA antibodies in convalescent sera. The study concludes that susceptibility to systemic meningococcal disease is related to a selective deficiency of humoral antibodies to pathogenic strains of meningococci, and that exposure to these organisms is crucial for developing immunity.