The NATO Lessons Learned Handbook

Welcome to the NATO Lessons Learned Handbook. The purpose of this handbook is to guide and assist you in fulfilling your role in supporting your organization and NATO to effectively learn from experience. This handbook uses NATO’s approach to Lessons Learned as the underlying model but has been written to be relevant to any organization.

This opening chapter sets the stage for the rest of this handbook by giving an overview of:

 What is Lessons Learned?
 Who Needs to Learn Lessons?
 What is The Role of a Lessons Learned Staff Officer (LLSO)?
 How to Get Started in Lessons Learned!




The term Lessons Learned is broadly used to describe people, things and activities related to the act of learning from experience to achieve improvements. The idea of Lessons Learned in an organization is that through a formal approach to learning, individuals and the organization can reduce the risk of repeating mistakes and increase the chance that successes are repeated. In the military context, this means reduced operational risk, increased cost efficiency, and improved operational effectiveness.


Lessons Learned describes more than just learning from experience. Learning must be used to justify changes that will lead to improved performance. This is made clear in NATO’s Joint Doctrine for Operations, which states:


“The purpose of a Lessons Learned procedure is to learn efficiently from experience and to provide validated justifications for amending the existing way of doing things, in order to improve performance, both during the course of an operation and for subsequent operations. This requires lessons to be meaningful and for them to be brought to the attention of the appropriate authority able and responsible for dealing with them. It also requires the chain of command to have a clear understanding of how to prioritise lessons and how to staff them.” – AJP-3(B) Allied Joint Doctrine for the Conduct of Operations1


Depending on your nation, HQ or organization, you will encounter the term Lesson Learned (and the acronym LL) applied both to the end result of a formal learning process or to one of the intermediate results, i.e. a lesson to be learned or a Lesson Identified (LI).


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