* When it's part of a proper noun:
* Peace Corps: This is the name of a specific organization.
* Peace Treaty: If it refers to a specific treaty, like the Treaty of Peace.
* Peace River: This is the name of a river.
* Peace Bridge: A specific bridge.
* When it's the first word of a sentence:
* Peace is a valuable concept.
* When it's used as a title:
* Peace is a powerful song by the band The Animals.
* A Time For Peace: This is the title of a book.
* When it's part of a formal name or title:
* The Peace Conference
* The Peace Prize
However, you generally don't capitalize "peace" when it's used as a general concept or idea.
For example:
* "We all want peace in the world."
* "The world needs more peace and understanding."