"Celtic" is such a wide-ranging term. Don't forget, the Celts once covered Western Europe. Bluegrass is a 20'th century phenomenon. (Remember the good ol' 20'th century?) One of the sources of Bluegrass is our "mountain style", and it shares one unique feature with what we think of as Irish/Scottish music. That is the "Flatted Seven" chord, for example the progression C-Bb-C, or Am-G-Am. These are the only styles that use that progression as far as I know, so it may be a musical feature that you can look for as a common link. == Johnny in Oklahoma City