There seem to be three options when writing a book in Word:
1. Using Word's Master Document feature.
2. Creating one humungous document.
3. Writing each chapter as an individual document and assembling them into a book at the end of the process.
I've never been able to get the Master Document feature to work satisfactorily. Probably just me, but I can't make it work. I've had equally bad results with creating one humungous file. Word tends to crash, or automatically reformat parts of the document, or incorporate infuriating "hidden" formatting. I find the safest way to work is to make each chapter a separate .doc file. Then assemble all the doc files just before publishing. But... you have to keep track of where the files are are on your disk, make sure you have the right version, and assemble them in the right order... I find it a frustrating organizational nightmare. Chapter by Chapter is a companion program to Word that goes a long way toward solving these problems.
Chapter by Chapter is a free program that helps you write a book in MS Word. It allows you to pull together multiple Word documents into a single longer one.
As you work, Chapter by Chapter gives you an outline view to the left of your editing window, so you can easily jump back and forth between various chapters. When your book is finished, Chapter by Chapter handles the task of compiling the documents.
Overall Chapter by Chapter seems to be a faster, more reliable way to assemble a book from multiple Word documents than using Word's frustrating Master Document feature, or creating one humungous book file.
You can download Chapter by Chapter here: