The WLS was built on a questionnaire carried out in 1957 about attitudes towards further education from graduating high school students. The study participants are a random sample of around 10,000 Wisconsin high school graduates from1957, born between 1938 and 1940. This is about a third of all graduates from this year. They have been followed up 5 times since the original questionnaire with telephone interviews and further questionnaires. Around 8,000 randomly selected siblings, the majority of whom were born between 1930 and 1948, as well as parents and the spouses of the graduates have also shared information for the study. There is only a handful of African American, Hispanic or Asian persons in the WLS, which reflects the very small number of minorities among Wisconsin high school graduates when the WLS began.