Capitalize a person's title when used with the person's name or as a direct address. The title is not capitalized when used generally.
Correct: the Duke of Edinburgh Dr. Fleming
Lieutenant Horatio Hornblower Efrem Zimbalist, Jr.
Incorrect: The Duke sends his regards.
(Used as a general word, not personal title.)
Correct: The duke sends his regards.
Incorrect: Thanks for calling, pastor.
(Title is implied because of direct address.)
Correct: Thanks for calling, Pastor.
Government officials' titles are capitalized when followed by a name or used in direct address.
Incorrect: We tried to get a glimpse of president Clinton.
(Title is used with name.)
Correct: We tried to get a glimpse of President Clinton.
Incorrect: What do you think of the situation in Rwanda, secretary?
(Title in direct address)
Correct: What do you think of the situation in Rwanda, Secretary?
Certain very high ranking government officials' titles are capitalized even when not followed by a name or used in a direct address when a specific individual is being referred to.
Correct: the President (e.g., of the USA or France)
the Chief Justice
the Queen (e.g., of England or the Netherlands)
Incorrect: The Constitution says the President must be at least 35.
(Not a specific individual being referred to.)
Correct: The Constitution says the president must be at least 35.
Correct: What do you think of the President's trip to Japan?
(A specific person is referred to here.)
Important words in compound titles are capitalized, but not prefixes or suffixes added to the titles.
Correct: the Under Secretary of the Interior
President-elect Clinton ex-Governor Meskill
Capitalize titles showing family relationship when they refer to a specific person, unless they are modified by a personal pronoun.
Incorrect: I can't wait to see cousin Angie.
Correct: I can't wait to see Cousin Angie.
Correct: Please let me go, Mom.
Incorrect: My Mom won't let us go. (Modified by my)
Correct: My mom won't let us go.