Development Dimensions International (DDI) is an international human resources and leadership development consultancy. DDI works with organizations to make changes related to leadership development, leadership selection, succession management, and execution and performance. The company is headquartered in Pittsburgh, Pennsylvania and has more than 1,100 employees throughout 42 offices in 26 countries. William C. Byham, Ph.D., is chairman, Tacy M. Byham, Ph.D., is CEO, and Ron Dalesio is president. DDI was founded in 1970 by William C. Byham, Ph.D., and Douglas Bray, Ph.D. DDI introduced the assessment center approach for identifying leadership skills. Byham’s article, Assessment Centers for Spotting Future Managers (Harvard Business Review), led to inquiries about the process, and later, Byham approached Bray about a partnership.