Accepting an Invitation

According to proper etiquette, how should you accept an invitation?
To accept an invitation, according to proper etiquette, you should write back in the style of the invitation. Cathleen Hanson, who is one of the owners and founders of the International School of Protocol, which teaches proper etiquette to children, adults, educators, and businesses, offers this example of the proper etiquette of acceptance of an invitation:

Your Name
Accepts with pleasure
The kind invitation of
Mr. and Mrs. Host
To dinner
Friday, the seventh of October
7 o'clock

If the invitation was sent to a couple but only one is able to attend, proper etiquette allows you to respond in this way.

Your Name
Accepts With Pleasure
Host and Hostess Names
Kind invitation for
Date and Time of event
But regrets that
Spouse's Name
Will be unable to attend

There is no need for further explanation as you can give the details at the event itself.
If it is an informal invitation, you may call to confirm that you will be attending. but make sure that it truly is informal and that you are not just assuming that because of being good friends with the host and/or hostess.

Consider this example of the importance of properly responding to an invitation. A bride is planning a wedding and sends RSVP cards to everyone including the bridesmaids and groomsmen in the bridal party. Some may not bother to respond, thinking, "We're in the bridal party; they know that we'll be there!" The problem with this is that the caterer does a head count based on the number of RSVP acceptances and even if he or she could take the extra time to go through the cards and make sure that all of the bridal party's invitations were sent back, she would still have no idea if they planned on bringing a guest. The bride is left, in the midst of last minute wedding planning, with the task of having to call everyone and make sure that they sent in their acceptances.

Cathleen notes that she has seen an increase in this trend of non-response to RSVP cards and says, "People are not responding, and it is just so rude." If the host/hostess had wanted to take the time to call everyone, that is how they would have made the invitations in the first place. It is a lot easier to count cards then it is to sit with a notebook on the phone and write down everyone's replies. That being said, if it is too late for you to accept an invitation by post, then a call, which is initiated by you, is better then nothing. Make sure to apologize for the inconvenience and ask if it is too late for you to accept. If you were too busy to reply to the invitation, even if it is only by phone, then proper etiquette means that you are too busy to attend. Make sure to send your regrets afterwards. Cathleen puts it best, "Truly, I know we are all very, very busy. However, it's a simple thing to pick up that phone."