If I have the following sentences, which version is correct:

  1. This chapter provides.... or
  2. This Chapter provides....

Note the capitalisation of 'c'.

  1. Chapter 1 provides....
  2. Chapter One provides...

Note the use of numbers

  1. This model was discussed in Chapter One
  2. This model was discussed in chapter one
  3. This model was discussed in Chapter 1
  4. This model was discussed in chapter 1

Note the use of capitalisation and numbers in the last part of the sentence.

Many thanks.

  • There is no "correct". Follow the rules in your style guide. If you don't have one then do whatever you want. – curiousdannii Aug 21 '15 at 5:57

Here is what I do:

When referring to a chapter generically, do not capitalize it:

This chapter talks about the exciting lives of carrier pigeons.

Refer to the chapter about carrier pigeons for more information.

When referring to a specific chapter, capitalize it:

The exciting lives of carrier pigeons are addressed in Chapter 5.

There are other purported "style guides" and grammar advice available via web search saying the same thing, but notably the Chicago Manual of Style disagrees:

Chicago prefers to lowercase the parts of a book, even if they’re titled generically, so in running text we would refer to “appendix A.”

  • I think that style of capitalisation is outdated. But in Victorian times, half your examples would probably have capitalised Carrier Pigeons, so I guess we have moved on a bit. – FumbleFingers Dec 23 '11 at 3:40
  • Could be, but this is what I still see used primarily in the things I read. Hardly a representative sample of The World, but apart from the CMoS reference (which even they dub a preference) I cannot find a definitive source. – Lynn Dec 23 '11 at 4:56
  • I wouldn't want to overstate the case against capitalisation when refering to a specific chapter (except OP's example two, "this Chapter", which does strike me as pretentious/archaic). All I mean is things seem to be moving against it, as even CMOS acknowledges. I should really have said "starting to become dated" above, if I'm honest. – FumbleFingers Dec 23 '11 at 14:39
  • This question on Academia SE addresses the same question, and the accepted solution corroborates what is written in this answer. – wizclown Jan 28 '19 at 11:00

This NGram should be sufficient evidence that people usually use digits. If nothing else, it avoids things getting really tedious if you needed to refer to chapter one hundred and twenty-eight when writing about some truly weighty tome (or one with a lot of short chapters).

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As regards capitalisation, I've no doubt people sometimes do it even in references within text, but I think it looks overblown and silly. Having said that, I would expect capitals if Chapter 1 was written as part of the actual chapter heading.

  • Ngrams seem to be your favourite evidence. – user11550 Dec 23 '11 at 0:24
  • 1
    It often is the easiest evidence to find :) BTW, ngrams for chapter one hundred and twenty-eight,chapter 128,Chapter 128 compared to the above shows that chapter 1 occurs about 200 times more frequently than Chapter 128 and about 500 times more frequently than chapter 128, and chapter one hundred and twenty-eight is a non-starter. – James Waldby - jwpat7 Dec 23 '11 at 0:38
  • @jwpat7: Astonishing. I really thought I was making up a totally ridiculous number for the sake of effect. But it only takes a tiny percentage of such books to show on NGram, given they'll have a marked tendency to refer to their own chapters (if you've got it, flaunt it!) – FumbleFingers Dec 23 '11 at 1:45
  • Looking up some of the Chapter 128 references, they are mostly, as I expected, various Acts and Statutes. Oddly, however, the term Chapter 11 is least-used among Chapters 1...12 in recent years. – James Waldby - jwpat7 Dec 23 '11 at 2:58
  • @jwpat7: One might well expect to see Chapter 128 capitalised much more often than chapter 12 then, since legal verbiage would be more inclined to aggrandise the word in their context. Which I don't disapprove of, but I think it would be a bit much for the average author to reference earlier text in his book with, say, (capital) Chapter 5. – FumbleFingers Dec 23 '11 at 3:36

As FumbleFingers stated, NGram evidence suggests that digits are used more frequently. Adding the other options, this NGrams additionally suggests using capitalization even in sentences: NGram comparison of capitalization and digit use

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