Lessons learned

Lessons learned (American English) or lessons learnt (British English) are experiences distilled from past activities that should be actively taken into account in future actions and behaviors.

There are several definitions of the concept. The one used by the National Aeronautics and Space Administration (NASA), European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) reads as follows:

The Development Assistance Committee of the Organisation for Economic Co-operation and Development (OECD) defines lessons learned as:

In the practice of the United Nations (UN) the concept has been made explicit in the name of their Working Group on Lessons Learned of the Peacebuilding Commission.

U.S. Army Center for Army Lessons Learned (CALL) since 1985 covers in detail the Army Lessons Learned Program and identifies, collects, analyzes, disseminates, and archives lessons and best practices.

In the military field, conducting a Lessons learned analysis requires a leader-led after-actions debriefing. These debriefings require the leader to extend the lessons-learned orientation of the standard after-action review. He uses the event reconstruction approach or has the individuals present their own roles and perceptions of the event, whichever best fits the situation and time available.

• After-action review
  • After action report
  • Debriefing
  • Hotwash
  • Postmortem documentation
  • Retrospective
• Benchmarking
• Best practice
• Business rule
• Experience curve
• Organizational learning
• Pre-assessment
• Risk management
• Strategic management

• Milton, N. J. (2010). The Lessons Learned Handbook. Oxford, UK: Chandos Publishing. ISBN 978-1-84334-587-9.
• Levy, Moria (2017). A Holistic Approach to Lessons Learned (1st ed.). Auerbach Publications. ISBN 978-1-351-23554-9. Retrieved 2024-01-24.

• NASA Lessons Learned