* Capitalization: She is the Chief Executive Officer of the company.
* Common: Sarah Miller, who you met last week, is the new chief executive officer of the company.
* Capitalization: Dr. Smith is the department head.
* Common: Dr. Smith, the department head, is attending the conference.
However, there are exceptions where the common noun loses its independent meaning within the proper title and is no longer capitalized.
* Common: the king of France
* Proper, no capitalization: the King of France