Throwing a formal party isn't as simple as calling a few friends and asking them to bring snacks. If you are attempting to throw a party with actual invitations, as opposed to an online invitation, you'll want to follow proper invitation etiquette. Addressing an invitation envelope may be one of the last details you think of when you think about invitations. However, a proper way to address the party invitation envelope exists.

Begin by writing out the recipient of the invitation in the middle of the envelope. Leave enough space for at least three lines of text. Spell out any abbreviations for titles if you want to be more formal. When addressing married couples, use the first name of the husband. For example, "Mr. and Mrs. John Smith" would be the proper way to address a married couple.

Write out the street address on the next line. Spell out abbreviated words like street, avenue or drive. If you need to add a apartment or unit number, you can start a new line if it won't fit on the street address line. An example of a traditional street address looks like this:

123 Chestnut Drive Apartment 2

Start a new line with the city and state. Don't abbreviate the state. If you can't fit the zip code on a single line, center the zip code on the following line. An example of a full address looks like this:

123 Chestnut Drive Apartment 2 San Diego, California 11111

Include your return address in the top-left corner of the envelope. You can abbreviate items in the return address, as you'll have much less space to write out the address.