Correct Grammar Uses for Jr., Sr., I & II

Updated February 18, 2017

When writing abbreviations associated with name titles, correct use of capitalization and punctuation provides clarity for the reader. Traditionally, when a child is given the same name as his father, the title “junior” is attached. The father, on the other hand, is deemed “senior.” Roman numerals are used to denote names transcending three or more generations: Timothy G. Wallace IV, for example.

Abbreviations for Name Suffixes

To abbreviate name suffixes such as “junior” and “senior,” the first and last letters -- “j” and “r” for “junior” and “s” and “r” for senior -- are written followed by a period. This abbreviation is used when a person’s given name is written in full such as John H. Smith Jr. When used in this context, the abbreviation is capitalized and a period follows it. If the name is written last name first, it should follow this pattern: Last Name, First Name Middle Initial., Suffix. For example, “Williams, Mark A., III.”

Comma Usage with Name Suffixes

In the past, a comma separated the last name from the suffix; however, most style guides no longer separate the last name from the suffix with a comma. For example, a name is written “Richard A. Black Sr.,” not “Richard A. Black, Sr.” A comma is used after the period following the abbreviation if the sentence continues beyond the name as the example above illustrates. Note that if a person goes by the name “Junior,” and it is not being used as a suffix, the name should be written out and not abbreviated.


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