Lessons Learned Library


The purpose of a Lessons Learned Library is to capture and share actionable learnings from marketing initiatives. While the framework here illustrates a ‘lesson learned’ from a single initiative, the real value comes from organizing a growing number of lessons in a structured and centralized way. A Lessons Learned Library can become an increasingly valuable resource for marketers to refer to when planning new initiatives. Lessons can be captured when initiatives or experiments end (as part of a Retrospective or Post-Mortem Meeting), or when issues unexpectedly arise. Marketing teams need to have the discipline and structure in place to capture and codify lessons consistently as part of their regular operations.


What have we learned before that might help us now?


  1. Start by documenting the Details of the project that your lesson relates to. Pay attention to the Tags used to categorize your lessons. What Tags will be most clear and helpful when searching?
  2. Capture the Background of the project to provide valuable context for your lesson. What would someone new to your team need to know to fully understand the project, situation, and lesson?
  3. Capture the Issue that impacted your project. This might be a specific marketing decision, experiment, or event. Make sure that this is an Issue that may be encountered in the future.
  4. Capture the result that the Issue had on the project. This may be an unexpected positive or negative outcome. Try to quantify the Impact, and make sure that it is material to your business.
  5. Finally, capture what you would do differently the next time this issue arises. What did you wish you knew before this project began? Make sure that your Recommendation is specific and actionable.


  • Consider using software to centrally manage how lessons are uploaded, tagged, and searched.
  • Consider incorporating a ‘Lessons Learned’ section in your briefs to highlight recommendations from past campaigns.
  • Monitor the Lessons Learned Library over time to ensure that it is being regularly populated and used.‍


Bland, D., Osterwalder, A. “Testing Business Ideas: A Field Guide for Rapid Experimentation”, Wiley, 2019.


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