A capital letter marks a name: a particular person, place or thing. You have used capitals since names of people and pets; here are the rules that trip up older writers. They rest on the difference between proper and common nouns.
| Capitalize | Don’t capitalize |
|---|---|
| Aunt Rosa, Mom (used as a name) | my aunt, my mom |
| Mayor Diaz, Doctor Rivera (title before a name) | the mayor, our doctor |
| the South, the Midwest (regions) | drive south, two miles east |
| Monday, July, Thanksgiving | summer, winter (seasons) |
| English, Spanish (languages) | math, science |
| the Mississippi River, Lincoln School | the river, our school |
Key idea
Capitalize proper nouns and the adjectives made from them, titles right before a name, family words used as names, and the names of regions. Don’t capitalize seasons, compass directions, titles used alone, or family words after my, your or our.
Why it works
Capitals let a reader tell a name from an ordinary word: “the South” is a region; “south” is a direction. “Mom called” uses Mom as her name; “my mom called” uses mom as an ordinary noun.
Worked example: Family words
“Mom and my dad came to the game.”
- Mom is used as a name (you could put her name there): capital.
- my dad follows my, so it is an ordinary noun: small letter.
Answer: Correct as written: Mom, my dad.
Worked example: Directions and regions
“We drove North to visit friends in the midwest.”
- north is a direction: lowercase.
- the Midwest names a region: capital.
Answer: We drove north to visit friends in the Midwest.
Common mistake
Capitalizing ordinary nouns for emphasis (“the Best Game Ever”), a family word after my (“my Uncle”), or a direction (“drive North”). Ask: is this word a name, or could a or the go in front of it as an ordinary word?