Last week, I read a book that was divided into three “parts.” I toyed with the possibility of doing this with my latest book.

It wasn’t too late. I was still on the final edit.

I asked myself what would be the reasoning behind dividing my book into parts and just what were the “rules” for doing so?

Here’s what my research showed:

Authors often divide their books into parts to show a natural shift in the story. For example, two people may be separated by a disaster in Part One, and then they may be reunited in Part Three.

Most authors use a three act division to shows where there is a natural divide in the story.

A part change may also show readers where they can stop for awhile, and pick back up later.

If a book spans a period of many years, imposing a structure by dividing it into several sections helps indicate the passage of time.

Simon and Marcus have known each other for almost twenty years. Dividing my book into parts will not only show the passage of time, but also how their relationship has changed from Chapter One through Chapter Twenty.

Divisions makes sense in this case.

Test it out. If your book takes place over a span of time, the story has natural shifts, or you think your readers would appreciate pauses between particularly tense action, dividing your book into “Parts” may be a good choice for you, too.