Forms of Address
How to address credentialed professionals
A lawyer is addressed as "[Full Name], Esq." professionally, or "Mr./Ms. [Full Name]" socially, never both Esq. and a courtesy title together. A professor uses "Professor [Last Name]" or "Dr. [Last Name]" if they hold a doctorate. An engineer or architect uses their name plus PE or AIA when the license is relevant, otherwise a standard courtesy title.
Checked September 10, 2026/7 min read
Written by Claire PostReviewed against USPS Publication 28
What is on this page6 sections
Credentialed professional titles share one underlying idea across every field on this page: a specific professional credential, Esq., PE, AIA, or a rank like Captain, can replace a general courtesy title in the right context, the same substitution logic that governs Dr. for a physician or Rabbi for clergy.
Where these titles differ from each other is when that substitution applies. A lawyer Esquire is professional-context only; a firefighter rank applies everywhere; a professor title works in essentially any context without needing to distinguish formal from social correspondence at all.
Step by step
Use Esquire for a lawyer in professional correspondence
"[Full Name], Esq." on the envelope for professional legal correspondence. Esquire replaces Mr./Ms.; never combine them as "Mr. [Full Name], Esq."
REBECCA T LINDQVIST ESQLINDQVIST AND PARTNERS LLP400 MARKET ST STE 900PHILADELPHIA PA 19106CorrectA lawyer, addressed professionally. Use a standard courtesy title for a lawyer socially
For a personal letter, "Mr./Ms. [Full Name]" is standard; Esquire is a professional-context title, not a social one.
Use Professor, or Dr. if they hold a doctorate
"Professor [Last Name]" works for any faculty member regardless of degree. "Dr. [Last Name]" is also correct and common for a professor who holds a PhD or other doctorate, and either is acceptable in most academic contexts.
Use PE or AIA for a licensed engineer or architect, when relevant
"[Full Name], PE" for a licensed Professional Engineer, or "[Full Name], AIA" for an architect who is a member of the American Institute of Architects, used in professional correspondence where the license or credential is directly relevant.
Use rank or role-based titles for public safety professionals
A firefighter is addressed by rank where one applies, "Captain [Last Name]" or "Chief [Last Name]," similar to police and military convention. A detective is addressed as "Detective [Last Name]," which functions as both title and role.
Quick reference
| Professional | Professional form | Social form |
|---|---|---|
| Lawyer | [Full Name], Esq. | Mr./Ms. [Full Name] |
| Professor | Professor [Last Name] or Dr. [Last Name] | Same as professional form |
| Engineer (licensed) | [Full Name], PE | Mr./Ms. [Full Name] |
| Architect | [Full Name], AIA | Mr./Ms. [Full Name] |
| Firefighter | Captain/Chief [Last Name] (if ranked) | Mr./Ms. [Full Name] |
| Detective | Detective [Last Name] | Detective [Last Name] |
Special cases
The rule above covers most people. Here is what changes for the rest.
Is an astronaut addressed with a special title?
There is no dedicated civilian honorific for "astronaut." A NASA astronaut who also holds military rank is addressed by that rank; a civilian astronaut is addressed by their standard professional title, such as Dr. if they hold a doctoral degree, plus "NASA Astronaut" noted on the line below if relevant to the correspondence.
Does Esquire apply to any lawyer, or only certain types?
It applies broadly to any licensed attorney in professional correspondence, regardless of specialty or seniority, though some attorneys, especially in-house or government counsel, use it less consistently than those in private practice.
Is PE required for every engineer, or only some?
PE (Professional Engineer) specifically denotes a state license, which not every working engineer holds or needs depending on their field and role. Only use PE after a name when the person actually holds that specific license.
Key terms on this page
- Esquire
- A professional courtesy title for a licensed attorney, used in place of Mr./Ms. rather than alongside it.
- PE
- Professional Engineer, a state-issued license credential added after a name in professional correspondence, held by some but not all working engineers.