Fear of strangers ( FOS ) during the infant's first year was studied in 46 "high-risk" offspring of index mothers with a history of nonorganic psychosis and in 80 demographically similar control offspring. FOS was measured in the home by a standardized test at 1 year of age and by repeated interviews with the mother during the first year. As compared with controls, the total index group, and the subgroups of offspring of mothers with Schizophrenia and Cycloid Psychosis, significantly more often showed a total absence of FOS in the test at 1 year, as well as during the entire first year. FOS at 1 year was unrelated both to serious active psychiatric disturbance in index mothers during the infant's first year of life, and the infant's sex, in index and control groups.