Supervisors often assume that “leadership development” equals a course or a program. Employees often equate it with access to continuing education funds. I wish both were true, because I have devoted my life to designing such programs and convincing organizations to pay for them.

But in my heart, I know that the highest-impact leadership development happens on the job, with developmentally appropriate assignments that stretch the employee (and the supervisor).

The list of projects an organization needs to have accomplished is the single best resource for developing current and future leaders.

Getting the developmental opportunity out of an assignment requires more than giving the project to an inexperienced person. The project goals must be clear enough for the inexperienced leader to make plans. The timeline, including milestones for progress and check-ins, must be explicit and monitored.

A developmentally appropriate assignment is an art form. Each step of the process may need to be repeated before the work is acceptable. Missteps are common, and many apologies may be required. Such an assignment is an experiment, with uncertain results and a process that might need to be reworked. And throughout the assignment, there must be a focus on what the employee is learning.

Here is the rub. Supervisors in every field are busy working on their own projects as they oversee the projects of others. Time is often the most precious resource, and assigning a project is a way to give away work.

But “developmentally appropriate” is code for “it takes time.” The developmental component requires time for reflecting on what is going well and what is not going well. Such an assignment does not “save” a supervisor as much time as the typical experience of assigning work to someone else.

Prioritizing leadership development requires that an organization have one eye on the present and one on the future. For the mission to be accomplished, there must be faithful dedication to the long view. Preparing colleagues to do an organization’s future work, while also making a meaningful contribution in the present, is the job of a supervisor. The board and senior leaders set this “present-future” bifocal vision.

When I have such a vision in mind, my highest work priority is to help colleagues who are feeling stuck. This present-future mindset enables me to be helpful and consider not just the presenting problem but what we both can learn. As a supervisor, I am not first an individual contributor managing my own projects; I have a responsibility to help others with their work, which is also about accomplishing the organization’s mission.

The term “developmentally appropriate assignment” seems to suggest that the assignee is the one learning. But in my experience, making such an assignment as a supervisor means I am also being developed. I get a chance to see a project through fresh eyes.

The coaching industry has produced many tools, books and training programs to help individuals learn from their work. These resources are worth exploring and using. But some aspects of leadership development cannot be outsourced. A supervisor can observe behaviors and give feedback that an external coach cannot.

Previously, I have written about making assignments that are “small enough to do and big enough to matter.” An employee’s capacity will likely grow over time. The development may not be linear, as life circumstances may demand a temporary focus on smaller, more defined tasks. But when the employee is ready, developmentally appropriate assignments can help with retention, even when an organization is not able to offer a promotion.

The new CEO of a sister agency once told me that no training program could possibly prepare a person to lead a complex organization during these changing times. I had to wonder, did he remember that designing and leading training programs is what I do?

But unfortunately, I think my colleague was right. A friend at one of the top leadership training organizations in the world once told me that formal training accounts for only about 20 percent of what leaders need to be well-developed.

The rest can be learned through challenging assignments. Offering a person the chance to start a new adventure or turn around an ailing program is a significant developmental opportunity. Muscles are strengthened in constructing a strategy, developing collaborations, designing experiments, evaluating results, managing people and so on.

In such situations, “training” involves providing time and space for the developing leader to learn from the experience. Any organization that creates a culture of offering developmentally appropriate assignments is investing in the future of its mission and its people.