Ask a long-time executive who has managed a team for the last 30 years and a younger entry-level manager what the definition of a leader is, and they will likely paint two different pictures.

With the ever-increasing presence of millennials (who are now the largest generation in the workforce) in the workplace, we’ve seen a shift toward more collaborative leadership and an inclusive work style that capitalizes on curiosity, transparency and purpose. Meanwhile, futurists preach that hierarchy is overrated, and the Zapposes and the Nikes of the world are paving the way with flatter or matrix organizational structures.

This leadership development revolution leaves business executives, particularly learning leaders, wondering if traditional training programs are delivering the appropriate return on investment. Given that in the U.S. alone, companies spend more than $15 billion annually on leadership development programs, it’s an operationally significant deliberation.

Consider this: Not only are your leaders (from new managers to middle managers to executives) the foot soldiers of your organizational culture, but they also maintain the competitive advantage and growth of your business. A leader’s impact on the bottom line cannot be ignored; leaders drive innovation and productivity, capitalize on business opportunities, and develop and retain top talent. In short, your leaders are so mission-critical, why would you not make an investment in their development?

But, have the required skills and expectations of our leaders changed significantly in the last 10 years? Absolutely, and organizations ought to shift their leadership training to reflect this new landscape.

The New Leadership Model: Evolutionary Development

Leaders’ responsibilities in today’s business environment are daunting. Even beyond generational differences, the digital revolution is reshaping consumer behaviors and demands, how we run our businesses, and the way we work. These transformations have even challenged the value of humanity itself, demanding higher-level human skillsets and deeper forms of sharing.

The need for leadership development is only deepening and broadening, setting the stage for a leader who thrives on and even encourages change and disruption. Yet, according to 2015 Brandon Hall research, 71 percent of organizations do not feel that their leaders are prepared “to lead their organizations into the future.”

Evolutionary development provides an ideology and approach for organizations to cultivate a new kind of leader who will not only adapt to dynamic business challenges but also foster the abilities of teams and individuals across the organization to thrive amid change. This new leader’s purpose is not to please cohorts or consolidate his or her power but to exercise wisdom, challenge the status quo, and envision the complex interdependence of systems and stakeholders.

As their vision develops, leaders diagnose opportunities and problems and re-engineer processes that align with the deeply-held purpose and values that govern their leadership. In doing so, they are already considering the impact of these changes on people’s behavior and mindsets. In fact, they use these transformative opportunities to foster deeper aspirational and behavioral alignment.

In its fullest form, this style of leadership is all-encompassing, focusing on how people think and feel, how they act, and how the larger system operates. But leaders can also be tactical and position their work at any of these three levels, situating themselves at the edge of that comfort zone where people are willing to travel to see what stands beyond.