[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
It gives me great pleasure to extend an invitation to our annual holiday party, taking place from 7 to 11 p.m. on Saturday, December 4 at the downtown City Club. At this event you will enjoy complimentary food and beverages, live music, and great conversation. Attire will be semi-formal, and feel free to bring a guest.
Please RSVP by November 22 to Gail Smith at 555-1212. We hope you will join us in celebrating the season and a successful year.
[Sender's first and last names]