How do you handle names with suffixes?

Dear Ms. Cards Etiquette,
Do you use Sr. or Jr. when writing to the woman when her husband was either a Sr. or a Jr.?
Mary Paull

Dear Ms. Paull,
In formal usage, yes, you do add the prefix Sr. or Jr. when corresponding with a woman whose husband was a Sr. or a Jr. For example, Mrs. John Smith Sr. is correct if her husband was Mr. John Smith Sr.

For a more informal treatment, it is proper to use one of the following:
Mrs. John Smith
Mrs. J. Smith
Mrs. Mary Smith
Mary Smith

Suffixes are used after names to provide more information about the person and are called post-nominal letters or post-nominal initials. These indicate a special position, degree, office or honor. The most popular social suffixes are senior or junior and are mainly used in the US. For correct usage, Jr. denotes a child of the exact same name as the parent. However, “Junior” is a popular nickname and often used even if the son’s name is entirely different from his father’s, as more a term of endearment than rank.

On an interesting note, there are no rules on what to do if the most senior member dies. No rules of etiquette or tradition have been determined so it is left to families to decide. Some families have the Junior “move up one” and become Senior, and others just keep ‘counting down the line.’ The legal name of Tom Cruise, for example, is Thomas Cruise Mapother IV

It is also interesting to note that very often, the ‘senior’ or ‘junior’ is not actually part of the legal name, it is simply added to help everyone avoid confusion. In other cases, the Sr. or Jr. suffix is part of the legal name and on the birth certificate.

Can women have Jr or Sr as part of their name if they are named after their mothers? You bet, although it is not nearly as common, as many women change their name when they marry. However, Anna Eleanor Roosevelt, Jr., and Carolina Herrera, Jr. are two women who have Jr after their names.

Thanks for your question, Mary!