The Leadership Challenge uses case studies to examine "The Five Practices of Exemplary Leadership", as researched and developed by Kouzes and Posner. Their first surveys for the five practices started in 1983, by asking people "What do you do as a leader when you're performing at your personal best?"[1] Over 30 years, they have done thousands of interviews and collected approximately 75,000 written responses.[3] Kouzes and Posner identified five common concepts in their survey, hence the five practices, which are: "Model the Way", "Inspire a Shared Vision", "Challenge the Process", "Enable Others to Act" and "Encourage the Heart".[2][4] Kouzes cites that the last practice, "Encourage the Heart", is the most uncommonly seen in leadership roles.