1. The inner envelope, with the names of the invited guests (sometimes omitted in informal invitations)
2. The outer envelope return address, with the name and address of the place you want gifts to be sent to
3. The outer envelope guest address, with the name and address of the guest(s) you’re sending the invitation to

There are several ways to address your invitations, in order of formality:

1. Caligraphy by yourself or someone you hire
2. Handwritten by yourself (or a team of you and your friends and family at an addressing party, my personal favorite)
3. Printed directly on the envelopes by the printer who prints the invitations (only available for return addresses)
4. Printed directly on the envelopes at home using your computer
5. Printed address labels (we recommend clear labels so you don’t have to find ones that match your envelopes)

You can use more than one method of addressing in combination.  For instance, you can have your printer print the return addresses in matching ink and font to your invitations, and then handwrite the addresses and inner envelope names or use labels.

I recommend making the decision about the method of addressing your invitations based on a combination of the formality of your wedding (remember, your invitations set the tone for your event), the formality of your guests (your grandmother may be shocked at seeing her address printed on a label), your budget, and the amount of time you have to dedicate to the task.  If you have the budget and you are having a very formal wedding, hire someone to do the addresses in caligraphy.  If you have a small budget, but have lots of time and a formal wedding, write the addresses yourself.  If you’re in college, have little money, are having a medium-formality wedding, and are planning to get married right after finals, by all means print those labels and slap them on.  It’s better to get the invitations to the guests less formally than to not invite them at all because you’re trying to handwrite the addresses in between classes and just didn’t have the time to finish the task.

UPDATE: My new favorite method is to find someone who can do short-run variable-data envelope printing.  There are few who can do this, and in Nothern California I may be the only one, but it basically means people come to me all day saying “I want the names and addresses printed on the front in the same font and color as the writing on the inside.”  When you call around, people will say “of course we can do envelope printing,” and what they mean is they’re picturing putting it through a press (which won’t work if you’re only printing one of each envelope) or they think they can put it through a copy machine (which will melt the “gum” and seal your envelopes shut, just like your home printer will.)  The machine I have is made by Xanté, and you could probably call them and ask where there is a similar machine in your state.  Or, as always, call me and I’ll get it done and done right.

Need a more specific answer?  Here are some factors to consider:

• Most invitations printers take between two and four weeks from the time they receive the order to the time it’s delivered, but they don’t guarantee delivery in that amount of time because they’re used to people ordering six months in advance.  Some kinds of invitations (like the kinds with photos printed on them) take a little longer to print than the traditional kind and if you’re doing something unusual give yourself more of a time buffer than you otherwise would.
• If you possibly can, add a week or more into your equation for mistakes.  No matter how diligent you are at proofreading, there could be a typo that no one catches.  We had a bride misspell her fiance’s name once, and the invitations had to be reprinted.  Occassionally the printer will make a mistake (printing on the wrong paper, using the wrong font or ink color, etc.), and the invitations will have to be reprinted.  If that happens, the printer will normally pay for the reprinting and rush the printing and shipping, but it will take time and you’ll be saved a lot of stress if you left some time for corrections.
• You will need time to address the invitations.  If you choose to handwrite the addresses, make sure you give yourself plenty of time to write.  I tell brides who are handwriting their addresses to give themselves about two weeks to do it.  If you’re printing address labels or printing the addresses directly on the envelopes, still give yourself a few days (I’d say about a week) to get it done.
• If you’re going to require an RSVP from your guests (like for a catered reception), add a couple of weeks to your calculations.
• A factor that most brides don’t know to consider when they’re deciding when to order their invitations is the geography of their guests.  People in different places have different expectations about how early a wedding invitation should arrive.  We suggest that brides sort their guest list by ZIP code and think about her guests by region.  Any time you send an invitation to someone who lives far away who might want to come to your wedding you need to give them plenty of notice so that they can get reasonable rates on their travel and lodging.  Try for 8 weeks before the wedding, if at all possible, if they need to fly in (especially internationally).  In the United States, people on either coast generally expect to receive wedding invitations 6-8 weeks before the event.  In some areas (like the Intermountain West) many people prefer to get invitations no more than two weeks before the wedding, possibly because the invitation is viewed as a reminder and if they get the invitation too early they’ll forget about it.
• Don’t forget to add in the amount of time it will take in the mail!  Usually it takes 2-3 days in the US, but if you send the invitations around a major holiday like Christmas it could take a few days longer.  If you’re mailing internationally, try to find out how long it will take to arrive and plan with that number in mind.
• The formality of your wedding and of your guests is another consideration.  The more formal the wedding and/or the guests, the earlier to invitations should arrive.  Eight weeks advanced notice is usually all that is expected even for the most formal wedding or from the most formal guest.

So, worst case scenario: 5 weeks for printing+2 weeks for reprinting because of typos+2 weeks for addressing+2 weeks for RSVPs+8 weeks before the wedding for guests who traveling in+1 week for time in the mail=Order 20 weeks before the wedding.

Best case scenario: 2 weeks for printing+0 time for reprinting+1 week for addressing+0 time for RSVPs+2 weeks before the wedding for informal guests who live nearby+2 days time in the mail=Order 5 weeks and a couple of days before the wedding.

Most people will want to order their invitations somewhere in between the worst and best case scenarios.  Hopefully the equations above will help you make an informed decision.  If you’re having a last-minute wedding and can only get your invitations to your guests a week in advance (or less!), don’t worry.  Hopefully you have a bunch of understanding friends and relatives who love you and don’t really care when their invitation arrives because they’re coming to the wedding with or without one.  Happy ordering!