Logic (which I was foolish to try to apply to anything involving the use of image data in Microsoft Word) told me that my best option would be to export the letterhead from InDesign as a .wmf file, since it’s A) vector-based and B) a Microsoft file format. Then, I should (“should” being the keyword) just be able to Insert>Picture>From File in MS Word with no problems. Unfortunately, the quality of the original vector artwork seems to be affected by this method, and by “affected” I mean “rasterized.” I have since learned that .wmf does not support Bezier curves, which is another reason to avoid exporting from InDesign to a .wmf.

Original vector artwork exported from InDesign to PDF (at 300%)

.wmf artwork inserted into Word and exported to PDF (at 300%)

So, it would seem that using a .wmf file is out, if we want to maintain our vector image. Next, I tried exporting an .emf followed by Insert Picture>From File into word and converted it to PDF. This version did, at least, yield a vector-based result. However, the paths seemed to be degraded somewhere in the conversion and smooth curves seemed to be converted into jagged segments. (Update: This is due to the fact that .emf also does not support Bezier curves and hence “converts” curves to a series of line segments.)

EMF converted from Word to PDF (300%)

Original vector artwork comparison with EMF exported from Word (800%)

At this point, you’re probably wondering, “Why didn’t you export your InDesign file to an .EPS?” Well, actually, that was the first option that I tried, but when I imported it into Word, the results looked like this…

EPS letterhead as it appears in MS Word

The moral of this story is that you can’t trust appearances in Word. When the same file that the image above was taken from is exported to a PDF, you end up with the following result.

EPS converted from Word to PDF (100%)

Same EPS converted from Word to PDF (300%)

When importing the EPS into Word and exporting to a PDF, we end up with our vector image information intact and unharmed, just as it was before we imported it into Word.

To make a long story short, if you want to import letterhead from InDesign into MS Word. Follow these steps to set up your Word Document

1. Export your InDesign file to EPS format.
2. Open a new Word document.
3. View>Header and Footer.
4. Insert>Picture>From File and select your EPS file.
5. Format>Picture
   1. Layout>Behind Text
   2. Size>Make sure Height and Width are at 100%
6. View>Header and Footer (to exit the edit Header/Footer)

Depending on the size of your letterhead, you will probably need to adjust your margins, so that your main text does not overlap your header image. After you’ve entered your text in Word, just export to a PDF, and you should have a clean vector-based letterhead.