Part one, Chapter two?

I have my Chapters broken up into Parts.

Normally I see Part One which is then broken into chapters. But do whatever you like. If your agent or editor doesn't like it, they'll ask you to change it. I can't see anyone rejecting a novel because they don't like how you numbered it.

"Part" to me seems more...significant. That's not the right word, but let me try to explain.

When I think of a chapter, I think of scenes. Maybe a day passes, maybe just a conversation.

But when I think of a part, I think of "acts." For example, my novel is broken into three parts:

1. Deirdre's spiral into depression and suicide attempt
2. 72-hour hold
3. treatment and recovery

Make sense?

In my present work, I use parts made up of several chapters. Each chapter is a scene, and each part has to do with a particular theme within the story. I think it's useful more for much longer works than my own piece, but then again I thought it was much longer when I originally wrote it than it really is.

I've written my book in "parts" instead of chapters. I have seven parts and each one ranges from 100-200 pages each. The parts are split into scenes, not chapters. The first part, A Mortal Weakness, is like a seperate novel within itself, with a beginning a middle and an end. It is about two characters who fall in love, have a child, then be forced to put their child into hiding shortly after, and at the end the mother dies. The next six sections are about the father searching for their lost son. Part two is set when their son is a baby, part three a teenager and parts four-seven are about the father's efforts to win his son's trust while he discovers the truth about his past. I wanted each section to be like a step in the character's journey. The first section details the story of his parents, the second his babyhood, the third his teenage years and lastly, at the end, the new person he becomes at the end of the book. I didn't intend to write the novel this way, it just sorta happened, I like it much more then using plain old chapters.

They're all just different names for the same thing

When I see Part I, II, III … I automatically assume it signifies a significant change in the storyline.

In an onddly slef-referential way, lots of Big Fat Fantasy use "Books" as an internal segmenting unit.

Like someone else said, it's about delineating pieces of the story, whether at the scene, chapter, part, or book level. It's gotta make sense, or represent major shifts in time, location, or POV.

My first book was broken into Parts > Chapters > Numbered sections/scenes. The Part changes signified a significant shift in the storyline...the ending of one thing and the beginning of another. (I was also reading a lot of King way back then and figured that was just the way you did it...hehe)