Traditionally, single-letter monograms represent the last name. That goes for both men and unmarried women. Often, modern single-letter monograms for young unmarried women will feature the first letter of their first names.
Men and women can also use a two-letter monogram with just their first and last initials.
FIRST AND LAST NAME- SALLY DONOVAN
Engaged couples should use the first name initials connected with an ampersand.
FIRST NAME OF EACH PARTNER-NATALIE & ETHAN
It is also appropriate for partners to use the initial of each first or last name.
LAST NAME OF EACH PARTNER-OLIVIA & CHASE
SAME SIZE LETTERS
Single men and women use the first letters of their first, middle and last name, in that order
FULL NAME IN LINE-ANDREW JAMES MALONE
LARGE SURNAME IN THE MIDDLE
For married couples, the surname initial goes in the middle, and the individual's first initials go on either side. The wife's first initial is on the left of the surname initial and the husband's first initial is on the right, as in ladies go first.
MARRIED COUPLE-EILEEN & DAVID WALKER
For married women, individually, it is tradition for the woman to use her married name initial as the middle initial in the three-letter monograms, with her first initial on the left and maiden name initial on the right.
MARRIED WOMAN-BETTY HARTMAN KAPLAN
Single or married men and women can also use their first name initial, married name initial, and middle name initial.
SINGLE OR MARRIED MAN AND WOMEN-LAURIE ANNE PIERSON
Same-sex partners can follow any of the rules above. If both are keeping their last names, both first initials of partners' last names are used together as the surname. They can also add their first initials on either side of the surname initials. So if CLH and FEN were same-sex partners, their monograms would be either of the following:
LAST NAMES-HARLOW NELSON
FIRST & LAST NAMES-CHARLES HARLOW & FRANCIS NELSON