Leadership development, a component of HRD, is becoming an area of increasingly important practice for all organizations. When companies such as Lawrence Livermore National Laboratory rely on knowledge workers for success, leadership becomes even more important. This research paper tests the hypothesis that leadership credibility and the courage to lead are important contributors to leadership effectiveness, where leadership effectiveness is defined by Laboratory measures of effectiveness including performance appraisal, ranking, salary, and subordinate evaluation. (Contains 4 tables.)