The Difference Between the Suffixes "Jr." or "II"

It's a basic genealogical question: If one wants to name their son after a relative, is it better to go with "Junior" ("Jr.") of "The Second" ("II") at the end of the name?

In my experience, the use of the term II generally indicates a son who has been named after a family member other than their father, such as a grandfather or an uncle. It is also sometimes used to identify the second male in a line of three with that name, although in that case Junior is usually the preferred term. As to whether it is required or not, I would tend to believe that it isn't. Terms such as Junior, II, III, etc. came into use to distinguish between two family members with the same name, generally implying that these family members are all still living. I believe in the case that the ancestor in question is many generations back in the family tree, it is really a matter of personal preference with the II being a formal way to indicate that there was a first, but not required since the great, great grandfather is long deceased.

I'm not an expert in naming etiquette, however, so here's what others have to say on the subject:

From Behind the Name: "Junior is used to distinguish a son with the same name as his father. The following conditions apply:

1. The Junior must be a son of the father, not a grandson.
2. The names must be exactly the same, including the middle name.
3. The father must still be living.

'II' is used whenever any close relative, including for example a grandfather or a great-uncle, shares the same name as the child."

Of course, there are also many who argue whether people move up the ladder as family members die i.e. Junior becomes Senior when the father dies, and III becomes Junior. Some, such as Miss Manners, say that yes, everyone does move up a notch [Martin, Judith. Miss Manners’ Guide to Excruciatingly Correct Behavior. Warner Books (1982)], while others insist that your formal name, including the suffix, does not change. But that's a discussion for another day...