Lessons log

One of the PRINCE2 principles is that a project must learn from experience. This means lessons should be actively sought, recorded, and applied throughout the project — not just at the end.

PRINCE2 uses the word “sought” intentionally to emphasise the need for the project team to look for relevant lessons, especially from previous projects, actively. Any helpful insights discovered are recorded in the lessons log, which serves as a repository for lessons that may benefit current and future projects.

At the start of a project, one of the first responsibilities of the project manager is to review lessons from other projects and enter them into the lessons log. These lessons can then inform the development of strategies, plans, and management approaches. Lessons can also emerge within the project — particularly at the end of each stage when the project manager should ask: “what have we learned?”

As the project progresses, the project manager updates the lessons log, and where appropriate, incorporates relevant lessons into plans, strategies, and work packages to improve outcomes.

Relationship with the lessons report

At the end of the project and each stage, the project manager produces a lessons report using information from the lessons log. This report is shared with the project board and is designed to help future projects avoid common mistakes and replicate successful practices.

Timeline

The lessons log is a living document that supports continuous learning throughout the project lifecycle:

• The lessons log is first created during the starting up a project process.
• The project manager gathers lessons from previous projects and key stakeholders to inform planning and strategy.
• The lessons log is continually updated during the project as new lessons are identified.
• At the end of the project, the lessons log is archived, and the most valuable insights are summarised in the lessons report for use in future projects.

Source data

The lessons log can be populated from various sources throughout the project, both within the current and previous projects:

• Lessons report from other projects
• Project mandate or project brief: The project mandate may also include a detailed lessons report
• Daily log, issue register, quality register and risk register
• Checkpoint report and highlight report
• Completed work package
• Stage plans with actuals
• Observations of project stakeholders/team.

Format

The lessons log can take various forms depending on the size of the project and the tools used by the organisation.

• A document, spreadsheet (often online), or a simple database
• An entry in an online project management tool
• A section within an integrated project register that also tracks risks, actions, decisions, assumptions, issues, and lessons (often referred to as a RAID log or similar)

The chosen format should make it easy to update, share, and extract lessons throughout the project.

Quality criteria

To ensure the lessons log is effective and usable, it should meet the following quality criteria:

• The status of each lesson clearly indicates whether it has been actioned or applied.
• Lessons are uniquely identified, include references to related products, and contain priority and stage information — helping the project manager easily identify which lessons are relevant for future planning.
• The project manager schedules regular reviews of the lessons log to ensure valuable insights are not overlooked.
• Access to the lessons log is controlled, as it may contain sensitive observations — including candid feedback about stakeholder behaviour (e.g., someone who frequently changes their mind).

A well-maintained lessons log supports continuous improvement and adds real value during planning and review.

Content

The lessons log should contain enough detail to make each lesson clear, traceable, and useful throughout the project and future initiatives:

• Unique identifier – A simple numbering system (e.g., 1, 2, 3…)
• Lesson/recommendation – A clear, concise description that’s easy to understand and apply.
• Type – A category to classify the lesson (e.g., team, supplier, legal, quality); organisations can define their own list.
• Priority – indicates importance, e.g., very high, high, medium, low, very low.
• Date recorded – when the lesson was first added to the lessons log.
• Relevant stage – the project stage in which this lesson may be particularly useful.
• Lesson status – whether the lesson has been used, actioned, or proven valuable during the project.

A well-structured lessons log supports learning and continuous improvement — both during and after the project.

Tips

Here are a few practical tips to help project managers get real value from the lessons log during the project:

• Make time to discover and revisit lessons — regularly reflect on new insights and follow up on existing entries.
• Raise the topic of lessons during work package reviews — this encourages ongoing learning and feedback from team members.
• Secure access to the lessons log, as some entries may be sensitive or confidential (e.g., “We will stop working with supplier X in October”).
• Add a “stage” column to your lessons log — while not part of the official PRINCE2 template, it helps identify when (e.g., next stage) a lesson is most relevant.

Consistently using and updating the lessons log supports smarter planning, fewer repeated mistakes, and stronger project outcomes.

—o—

Written by Frank Turley.

If you have questions or doubts after using this wiki, you can ask for help on the Facebook or LinkedIn study groups.