 Ter Horst attended school in The Hague and subsequently studied at University of Amsterdam where she obtained a MSc degree in psychology.In 1984 she received a PhD degree in social science on her thesis concerning the question how people who never go to the dentist can be made to do so.Between 1986 and 1994 she was associate professor of Social Dentistry at the subfaculty of Dentistry of the University of Amsterdam.