In the book, "Scottish Clan and Family Encyclopedia" by George Way of Plean and Romilly Squire,pg. 369 is a listing for Caldwell. It says the name comes from the old English 'cealdwielle'. It also says 'Caldwells of that Ilk' "continued for many hundreds of years in good reputation, by inter marriage with many honourable families and ended of late in the person of John Caldwell of that Ilk, one of the commissioners for the shire of Renfrew about the year 1693". A branch of the family emigrated to County Fermanagh in Ulster where they bought property and named it Castle Caldwell. Sir James Caldwell fought with William of Orange in Donegal in 1690. I remember reading in another book that Caldwell was a sub-clan of another family clan, but I can't find it right now. Does anyone know which one?