What is a Theory of Change?

A way to map how change happens - and how we know if it’s working

A Theory of Change (ToC) is a structured way of describing how and why a particular change is expected to happen. It maps out the steps between what a service or project does and the change it wants to see. It shows the links between activities, outputs, outcomes, and longer-term impacts — so we can track whether we’re on the right path and adapt when we’re not.

That might sound quite formal, but it’s actually something we all do, often without realising.

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Everyday theories of change

Think of the last time you tried to set yourself up for a good start to your morning. You possibly did something like this:

• Set your alarm early

• Planned time for a stretch or a walk

• Made space for breakfast before leaving the house

Why? Because over time, you’ve developed a theory (even if unspoken) that says: “If I get up early and have time to ease into the day, I’ll feel more grounded and less rushed.”

That’s a theory of change.

It’s based on past experience, a sense of cause and effect, and a belief that one thing leads to another. But it’s also not guaranteed. Some mornings, that alarm rings… and things don't go to plan!

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Why a ToC needs testing, too

A good Theory of Change recognises that things don’t always go as expected. It invites us to ask:

• Are our assumptions holding true?

• Did our action (setting the alarm) lead to the output (getting up early)?

• Did the output lead to the outcome (starting the day feeling calm and in control)?

• What other factors got in the way (e.g. traffic jams, sudden responsibilities, a bad night’s sleep)?

By mapping this out in a transparent way, a Theory of Change gives us a shared starting point for learning, helping teams reflect, adapt, and make better decisions as they go.