Much research on charisma investigates its relationship with leadership. Studies suggest great leaders are a mix of personal charisma, the right situation and devoted followers. People need charisma to become great leaders, it seems, yet charisma alone can't make a great leader--only break one.

Why? Partly because charismatic people's power depends on others' perceptions, and those perceptions are malleable, says a 1999 study in the Journal of Applied Psychology (Vol. 84, No. 3). People rated leaders as charismatic only if they believed the leaders sacrificed their own interests for a cause, says study author Stefani Yorges, PhD, a West Chester University psychology professor. She cites as an example former Chrysler head Lee Iacocca, who rejuvenated the slumping company in the 1980s while giving himself a one-dollar annual salary--an act employees found austere, genuine and charismatic.

Situational or not, charisma may serve as the extra boost that turns average leaders into great ones. Research by Robert House, PhD, a management professor at the University of Pennsylvania, posits that charismatic leaders exhibit greater self-confidence, persistence, determination, passion and optimism than their run-of-the-mill counterparts. Charismatic leaders also consider other people's emotional well-being, and they intellectually stimulate and empower followers through techniques such as goal-setting, Yorges says. "Their goal is to create followers who will eventually lead themselves," she explains.

Some researchers suggest charisma isn't enough to make successful leaders. "If leaders are only charismatic, they'd rather keep power for themselves," Yorges notes. Psychologist Robert Hogan, PhD, agrees, suggesting that charisma has a dark side resembling narcissism. Hogan, the head of consulting firm Hogan Assessments, which measures personalities of potential corporate employees, says narcissistic people often land leadership jobs, such as CEO, but fail as leaders in, for example, building a company.

"People who score high on narcissism are bold, assertive, attractive and powerful--what we would consider charismatic," Hogan says. "But they can fail as leaders because they never admit mistakes. It's a myth that great leaders are simply charismatic. They are also humble."