Donald O. Clifton (1924-2003) was named by the American Psychological Association as the grandfather of Positive Psychology and father of Strengths-Based Psychology .  He looked to find what was right with people, choosing to study successful people and how they functioned, with the goal of helping others enhance their own success.

In 2001, together with Tom Rath and a team of scientists from Gallup, Donald O. Clifton used over 40 years of research in human strengths to develop the Clifton StrengthsFinder Assessment.  Grouping the most common talents together into 34 themes, they created language to help people discover what's great about themselves.