1. The Rules for Capitalization Language Handbook pg. 616
Capital Letters
The Rules for Capitalization
Language Handbook pg. 616

2. Objective:
To capitalize the first words of sentences in a paragraph and to add appropriate end marks.
To correct capitalization errors in sentences.

3. Using Capital Letters Correctly
21a. Capitalize the first word in every sentence.

4. 21b. Traditionally, the first word of a line of poetry is capitalized.
21c. Capitalize the first word of a directly quoted sentence.

5. 21e. Capitalize the pronoun I and the interjection O.
21d. Capitalize the first word in both the salutation and the closing of a letter.
Although it is rarely used, O is always capitalized. Generally, it is reserved for invocations and is followed by the name of the person or thing being addressed. You will more often use the interjection oh, which is generally not capitalized unless it is the first word in a sentence.
21e. Capitalize the pronoun I and the interjection O.

6. 21f. Capitalize proper nouns and proper adjectives.

7. In proper nouns of more than one word, do not capitalize…
short prepositions (generally, ones with fewer than five letters, such as in, on, and with)
articles (a, an, the)
coordinating conjunctions (and, but, for, nor, or, so, yet)
the sign of the infinitive (to)

8. (1) capitalize the names of persons and animals.
For names having more than one part, capitalization may vary.

9. (2) capitalize initials in names and abbreviations that come before or after names.

10. (3) Capitalize geographical names.

11. Words like city, island, river, street, and park are capitalized when they are part of a name. When words like these are not part of a proper name, they are common nouns and are not capitalized.

12. (4) capitalize the names of organizations, teams, government bodies, and institutions.
Do not capitalize words such as democratic, republican, or socialist
when they refer to principles or forms of government. Capitalize
these words when they refer to specific political parties.
The Democratic candidate will debate the Republican
candidate tonight.

13. (5) capitalize the names of historical events and periods, special events, holidays, and other calendar items.
Do not capitalize the name of a season unless it is personified (“Here is Spring in her green dress!”) or used in the name of a special event (Fall Festival, Spring Jubilee).

14. (6) Capitalize the names of nationalities, races, and peoples.
Canadian, Korean, Caucasian, Asian, Kurds, Zulu, Seminole
(7) Capitalize the names of religions and their followers, holy days and celebrations, sacred writings, and specific deities.

15. (8) Capitalize the names of businesses and the brand names of business products.
(9) Capitalize the names of planets, stars, constellations, and other heavenly bodies.

16. (10) Capitalize the names of ships, trains, aircraft, and spacecraft.
(11) Capitalize the names of awards, memorials, and monuments.

17. (12) Capitalize the names of particular buildings and other structures.
Generally, do not capitalize words like hotel, theater, college, high school, and courthouse unless they are part of a proper name.

18. 21g. Do not capitalize the names of school subjects, except the names of language classes or course names that contain a number.

19. 21h. Capitalize titles.
(1) Capitalize a person’s title when the title comes before the person’s name.
Generally, a title that is used alone or following a person’s name is not capitalized, especially if the title is preceded by a or the.
Titles used alone in direct address, however, generally are capitalized.

20. (2) Capitalize a word showing a family relationship when the word is used before or in place of a person’s name, unless the word follows a possessive noun or pronoun.
(3) Capitalize the first and last words and all important words in titles and subtitles.
Unimportant words in a title include: