Leadership has become the most important element in the management of organization. The contemporary management has become very complicated. The need of the organizational leadership is essential to simplify this complexity. Now, the leadership can be developed in organizations through training programs and managerial solutions. Therefore, leadership development handbook has been authored to guide the organization to develop programs that optimize the leadership effectiveness and leadership competence.The introduction of this handbook explains the major styles of leadership that coexist in the real field. Particularly, the introduction will explain the advantages and disadvantages of every leadership style and their impacts on the organizational performance. Then, the introduction will define the leadership development process (LDP). LDP includes three phases will be explained every phase in a separate section. The three phases of LDP are following:1. Leadership Assessment2. Leadership Promotion3. Leadership EmpowermentIn the leadership assessment section, the handbook will explain three subjects. First subject is the assessment instruments, where the handbook explains the advantages of some assessing instruments such as surveys and interviews. Second subject is the evaluation of leadership effectiveness, where the handbook explains how to evaluate the leadership behavior in an organization. Third subject is the measurement of leadership competence, where the handbook explains how to measure the competence capacity and leadership understanding of leading, planning, organizing, and controlling.In the leadership promotion session, the handbook will explain two methods to promote the leadership: 1) the development of leading mentality, and 2) the development of leadership behavior. The first method explains how leaders can use emotional intelligence, critical thinking, and strategic thinking to enhance their conceptualization of leadership. The second method explains how organizations can develop leadership behavior by using three ways of leadership development: (1) training programs, (2) developmental assignments, and (3) human-engineering laboratories.In the leadership empowerment session, the handbook will explain three managerial applications to empower the leadership effectiveness. First application is the quality assurance programs, where the handbook explains how to improve the quality of leadership through improving the quality of works systems. Second application is the corporate governance, where the handbook explains how to systemize leadership by using committees of governance. Third application is the balanced scorecard, where the handbook explains how to empower leadership by using a system of strategic management.