For the past 20 years the author and his associates have worked with over 1600 organizations to improve safety performance. In the course of this work, we have discovered that organizations optimize their efforts when they provide and support strong roles at each of three levels: the front-line employee, supervisory, and senior manager levels. These three roles, when appropriately engaged, make up a cord of three strands that is not easily broken. Of these three areas, the leadership role has proved not only to have the greatest impact on safety improvement but also the most complex to understand and influence. One striking example of this is seen in the study of sites using the same improvement methodology. Even when compared by industry, site size, and systems, some organizations achieve steady improvement whereas others consistently struggle. More than any other factor, the quality of the organization's leadership-in particular its influence on the organizational culture-determined the level of success achieved. By organizational culture we mean the shared common values that drive organizational performance, more commonly defined as "the way we do things here." Culture applies to many areas of functioning, is generally unstated, in the background, and slow to change. Even though it is generally recognized that leadership is important to performance, the "how" of that leadership is often debated. What makes a leader effective at influencing and improving safety? What are the qualities of such a leader? What are the key tasks that a leader must perform to generate desired results? Although this paper focuses on these questions with respect to senior leaders, the principles discussed are applicable to all levels in the organization. (c) 2006 Behavior Science Technology.