Capitalization is required for proper nouns, such as names, but sometimes words can be proper nouns or common nouns. Family titles, such as mom and dad, fit into this category.
The general rule is to capitalize a family name when it is used as a name, and not to capitalize when it is a common noun. A good tip is to look if there is a pronoun or article (e.g., the, your, his, etc.) preceding the title. If an article or pronoun is there, don’t capitalize (e.g., your mother is pretty). If there is no article or pronoun, then the word is being used as a proper noun and is capitalized (e.g., that dress looks good on Mom).
Side note: Be aware that when you are using a family name as a proper noun in dialogue, sometimes a comma is required as well.
Frye’s father, Mark, experienced chest pains and suffered a heart attack at the stadium just before halftime. His mother, Dana, let Ian know what was going on. Ian went into the stands to check on his dad, who was being attended to by emergency medical personnel. [Deseret News]
For a while, neither Dad nor I felt much like picking up the phone. Then, two years after we lost Mom, I was home for Christmas and saw Match.com installed on Dad’s phone. [Huffington Post]
For Weaver, it “tidies up a few of the loose pieces on the family tree,” and his daughter says she “thanks Dad for her high cheekbones.” [Guelph Mercury]
Thanks, Mom and Dad. [Post Independent]
Writing Mini-Lessons: Four Capitalization Confusions
Most of you are very knowledgeable about capital letters. You understand the basic differences between common nouns and proper nouns—that the names of specific people and places should be capitalized. You recognize that first words of sentences and first, last, and important words in titles require capital letters. However, there are a few lingering problems with capitalization, places where capitalization has proved confusing. Here are four rules about capitalization to clear up a few capitalization misunderstandings:
- School subjects, such as math and science, don’t take capitals: they are general fields of study, not titles of specific courses. An exception is English, which does take a capital because it is the name of a language—as are Spanish, French, and German. Later in your schooling, when you write titles of specific college courses, you will capitalize: History 101 or Earth Science 203.
- Seasons of the year are not capitalized: It was a beautiful spring day; I love summer best; the leaves are colorful in fall; we will travel south in winter. However, specific seasonal events and occasions do take caps: Fall Carnival or Winter Formal.
- The directions of the compass are not capitalized: north, south, east, and west aren’t capitalized unless the writer is referring to a specific place or region: the Northeast, the Southwest, or East Petaluma.
- Words like mom, dad, grandma, and grandpa sometimes require a capital and sometimes do not: it depends on the context in which the words are used. Here’s the rules: If there’s a personal pronoun—my, our, her—in front of the family role, there’s not a capital letter. It’s merely an identification, not a name: my mom, our dad, here grandma—like his dog, their cat, my eel. However, if there’s no personal pronoun, and you’re using the word as though it’s a first name, then do capitalize it: I asked Mom for some cash; I hollered for Dad to come help me with my homework; she loves Grandma’s home-baked pies. A good test is to substitute the first name of the relative in question. If your mother’s name is Diane, and you can say in your sentence about her, “I asked Diane for money,” then mom will be capitalized. But if your original sentence was “I asked my mom for money,” when you substitute Diane for mom, you get “I asked my Diane for money.” This cues you that in this case, mom will be lowercase—a common noun, not the proper noun of a person’s name.