Great organizations happen because of great people, and the staggering need over the next decade or more for great people to fill leadership positions is one of the most critical challenges nonprofit organizations face.

Two years ago Bridgespan’s report, The Nonprofit Sector's Leadership Deficit, projected that 640,000 new senior managers would be needed in the sector between 2006 and 2016. The shortfall is too large to be filled exclusively from within the current ranks of nonprofit organizations or even the sector; bench strength is simply inadequate to accommodate growing demand.

The MetLife Foundation/Civic Ventures Survey of Nonprofit Employers shows that recruiting and hiring talent are rated a top human resource challenge. We urge nonprofit leaders to pay attention to the implications of the leadership deficit; to the millions interested in encore careers; and to a few key lessons below.

Throughout our economy there is more mobility around talent than ever before—and that includes career switchers. The large talent pool of women and men interested in encore careers potentially expands the number of candidates available for nonprofit leadership and frontline positions. It is in the sector’s interest to encourage them, especially those with functional expertise (e.g., operations, finance, human resources, and marketing). When it comes to high-level managers, corporate bridgers offer the skills and leadership experience many nonprofits need in these areas.

Nonprofits must cast a big net. An effective recruitment strategy for a key leadership position should be seen on a long runway. These choices should not be made for the sake of expediency. New intermediaries like the Bridgespan Group and its Bridgestar initiative, among others, are beginning to enhance nonprofits’ recruiting capacity by helping them recruit from a broad talent pool.

Nonprofits should be leaders in recruiting people of all ages and diverse backgrounds. This means recruiting from outside when required, while also working to retain top employees. Employers need to avoid Jim Collins’ “tyranny of the ‘OR’” from Built to Last—thinking that they can either find their leaders within their organization and elsewhere in the nonprofit sector or by looking outside, among younger people or older people looking for an encore career. Nonprofits can and should look in all places, because responsibly carrying out their missions requires them to find the best. And successful organizations thrive on diversity of experience and perspective.

Nonprofits need to put skepticism, however understandable, aside and be open to career switchers. To build strong organizations, nonprofits would be shortsighted to turn away from the large potential talent source currently outside the sector. For instance, they would be foolish to screen out an encore careerist with relevant experience just because she hadn’t previously worked in a nonprofit. Cloning prior staff—and especially prior leaders—may feel safe, but it doesn’t necessarily prepare an organization for the challenges of the future.

Organizations underestimate the importance of their culture at their peril. Culture is the everyday; it shapes how organizations function and interact and defines behavior. Nonprofits must screen for candidates who, beyond having the right skills and experience, will fit the organizational culture and eventually become culture carriers themselves.

Career switchers can contribute to an organization’s culture of mentoring—and success. The secret sauce in organization-building extends to developing employees and includes a culture of mentoring—where mentors and mentees learn from each other. This is an avenue for success with career switchers who can teach and bring new skills while also learning about the organization and its culture. When the culture of an organization supports and promotes mentoring, the benefits go both ways.

Nonprofits must recognize the elephant in the room: Recruiting and retaining the best requires a serious investment. There’s no other way. Business lives with this premise everyday, but the nonprofit world is often short on resources to invest in training and development, employee support, and rigorous recruitment strategies. Such investment is essential. It’s time for nonprofits and their funders to increase investments in human talent. This is more than a human resource challenge; it needs to be accepted as an organizational priority and strategic imperative from the top down.

None of this is easy, but it has to be done if organizations hope to deliver real impact.