The study investigated the associations between social and psychological factors in childhood and adulthood and the occurrence of adulthood hay fever in a longitudinal birth cohort study. A total of 5780 participants with data on parental social class, childhood hay fever up to age 7 years, childhood cognitive ability at age 11 years, educational qualifications at age 33 years, personality traits, occupational levels and adult hay fever (all measured at age 50 years) were included in the study. Using logistic regression analyses, results showed that childhood hay fever identified by medical doctors and traits Emotional Stability and Conscientiousness were significantly and independently associated with the occurrence of hay fever in adulthood.