1. Undertook various studies on moral development
2. Used interviews to collect qualitative data
3. Conducted a longitudinal study that followed the development of the same group of 75 American boys for 12 years, who started the research between the ages of 10 and 16
4. Boys were 22-28 at the end of the research
5. Used interviews to assess moral reasoning, including the use of moral dilemmas
6. Studied people in Great Britain, Canada, Taiwan, Mexico and Turkey for a cross-cultural comparison