Save The Date Envelopes

I would address them the way you would the invite envelope.

Address them to the people that are invited IE:

John & Jane Smith (or use mr & Mrs if you perfer)

and if the kids are invited, add their names underneath

so:

John & Jane Smith

Jill & Jack

Save the dates are a bit more informal than the actual invitations, but should still be addressed to everyone you're expecting to invite to wedding. Be more casual but respectful

I did mine totally informal. I've read on here lots that you should address them like invites, but I definitely didn't. It was my way of setting them apart from invites and just making them seem like fun little reminders

So I did something more like..

John & Dana Smith

or on some of the older couples I did something like..

Mr. & Mrs. John Smith

Also, if you have anyone on the fence of whether you will invite them or not, do NOT send a save the date. Once you send them a save the date, they MUST be invited to the wedding. I sent out my save the dates a couple weeks ago, and we didn't send them to 3-4 people that we are still iffy on them making the cut.

Address married couples: Mr. and Mrs John Smith, and if you are inviting the family put the names of the children by age on the second line. For adult couples who live in the same residence, and are not married, list alphabetically by last name such as: Miss Ashley Jones and Mr. David Ross.

Just a note: make sure you know the names/titles that people prefer, including both members of married couples--don't assume that every married woman has changed her name. Nothing should be addressed to us as Mr. & Mrs. B, because I am not "Mrs. B."

Similarly, if you're inviting a friend and their significant other, you should find out the SO's name so that they can be included by name, not just as "plus one."