If your relatives or friends are engaged to be married, their fiances (or fiancees) must be invited; their live-in romantic partners must be as well. However, if they are only dating, you need not invite their boyfriend or girlfriend. Should you decide to include some dates and not others, draw your cut-off line at a clearly identifiable place and communicate it to everyone who is not allowed to invite someone to accompany them.

Beware, many unmarried people find it tremendously upsetting to not be allowed to bring a date. Prepare them for the idea and pay careful attention to where the singletons sit during dinner.

As for your attendants -- letting them bring an escort would be a considerate gesture. It's not required, but they've done a lot for you.

Though most etiquette advisors will say that inviting one of your first cousins means you should invite them all, this rule does not mean you must treat both sides of the aisle the same.

Elizabeth Howell of the Emily Post institute confirms: It's best to treat each family according to the closeness (and the reality) of that family's ties. Your family won't be as aware of the family-tree breakdown on his side; but should they discover that his first cousins were included while yours were not, there's a simple reply: "His family is much closer than ours is."

"It all depends on the size and location of the wedding and the size of your department," says Elise Mac Adam, author of "Something New: Wedding Etiquette for Rule Breakers, Traditionalists, and Everyone in Between" (Simon Spotlight Entertainment; 2008). If you're throwing an intimate destination wedding, it's unlikely that your boss would be insulted to be left off the guest list. But if you're throwing a rather large affair and work at a small organization, it's polite -- not to mention smart politics -- to invite the head honcho. "A courtesy invitation can't hurt," explains Mac Adam. "And your boss will be happy to have been thought of." Finally, don't worry that it will be seen as a ploy to score a present; most managers, regardless of whether they've been invited, give wedding gifts to their employees who marry.

Let your invitation do the talking, says Anna Post, author of "Emily Post's Wedding Parties" (Collins; 2007). Let's say you've chosen not to include kids younger than 5, and your friends have an 11-year-old and a 4-year-old. You'd write the friends' names and the older child's name on the inner envelope, indicating that the youngest isn't invited. If you're worried guests won't get the message, call beforehand. Says Post, "You can say, 'We just sent the invitations and we're excited to have you join us, but we've decided not to include young children. I wanted to give you advance notice so you have time to find a sitter. I hope you can make it!' " Don't grant any exceptions; that would be rude to guests who've abided by your wishes.

It's very common nowadays for brides and grooms not to invite children. Increased competition for wedding venues has pushed prices for sit-down dinners way up. But what about teenagers? There's no clear guideline from etiquette -- you could use the "old enough to receive their own invitation" rule (which is 18, per Crane's, and 16 per other sources; but we've also seen 12 given as that age). If you set the cut-off at 18, however, you may really hurt the feelings of any younger teens. Teenagers especially hate being treated like children, so they may resent it even more.

Etiquette's rule of reciprocal entertaining is pretty strong. If your friends' wedding was recent, and you are still close -- and if your wedding is on a similar scale as theirs, or is larger -- they should already be on your guest list. But if your friendship has faded some since their nuptials, or if your wedding is of a smaller size, it is completely appropriate to leave them off your guest list.

Exercise some caution if you have mutual friends who are invited; alert those people to the restriction in your guest list, so that they won't gush on and on about your wedding in front of those not invited, and create an awkward moment for everyone.

Do you need to invite them? The short answer is no. Simply think of this gift as a message to you and your groom that you are important to this person.

If you're worried that she's expecting an invitation, review the situation with whoever is closer to them (if it's a friend of your mother's, ask her). She will know what sort of information has gone out to her friends about the guest list -- in fact, that information has likely come from her -- so she'll be your best guide to what her friends' reaction is likely to be. She'll also tell you if inviting her friend will open a can of worms (for example, will your mother then have to invite her entire yoga class?).

If you do decided to add this person to the list, make sure her invitation goes out right away if they've already been mailed.

Even though your choice of what to serve really doesn't require an explanation, it's not a bad idea to give your guests a heads up about alcohol, says Post. The best way is by word of mouth, she says; ask your family and your wedding party to pass along the information as they would any other details about the wedding and reception. You could also casually mention it to guests with a simple "By the way, there won't be any alcohol served at the reception."

If your guest list is large or you prefer to let people know in writing, add a discrete note on the reception page of your wedding website: "Please know that alcohol will not be served." The same wording could also unobtrusively appear on any insert you include with your reception invitation, such as directions to the venue or other logistics, but Post says this should be a last resort. Never include it on the wedding invitation itself.

The easiest solution is to provide a card for each guest. That would certainly eliminate any difficult decisions. However, this would mean you'd need almost twice the display space, which could pose a problem if your list is large.

A more space-saving option: use a single seating card for each twosome and follow the format you used when addressing your invitations. If the couple live together or are married, put the woman's name before the man's (and be sure to alphabetize by her last name). If an established couple does not share an address, however, each should get an individual card, just as they received their own invitation. If you sent an invitation with an "and Guest" notation, simply ask for the name of the person your friend is inviting before the wedding and make sure the date gets a separate seating card.

Open seating may seem as if it would be fun and spontaneous, but guests shouldn't have to feel like they're the new kid in the school cafeteria. You don't want them to be stranded, without somewhere welcoming to sit, or rushed into claiming territory.

That said, you needn't micromanage -- only the most formal receptions require place cards at each setting, says Joyce Westin Dunne, a Chicago wedding planner. Assigning only tables and letting guests choose their chairs is perfectly acceptable.

Should you decide to forgo table assignments, remember that your guests will take longer to seat themselves. And you'll need to account for more settings than number of guests, since it's inevitable that there will be incomplete tables (for example, six guests seated at a table of eight).

If you send a save-the-date to someone, but then you have a falling out, are you still obligated to invite them to the wedding? It's a pretty big no-no to tell someone about a party and then not invite them. It's right up there in the top etiquette violations. The question you need to ask yourself is "how serious is this falling out?" To not invite them would be a signal that you didn't want them in your life at all anymore. To invite them after all would be an olive branch -- a sign that you consider the estrangement to be temporary. So before you renege on the invitation decide which message you want to send?

Regardless of how formally you are constructing your invitations, adding the word "cocktail" before "reception" is the most straightforward way to let your guests know that dinner will not be served. Traditional wording might read something like: "A cocktail reception will follow the ceremony" or, more casually, "and afterward for cocktails and hors d'oeuvres."

The start time for your reception will also help clue in guests. "Set the event during cocktail hours -- that can be 4 to 6 p.m. or 5 to 7 p.m. -- and anticipate that it's going to be a shorter reception than usual," says Mac Adam. Whatever time you choose, wrap things up, including the cake cutting, no later than 8 p.m. so people will still have time for dinner.

Unfortunately, this isn't a rare occurrence, which is why it's important that your contract have all the details in writing. Even better, have a picture taken of the final chosen design, suggests Karen Bussen, author of "Simple Stunning Wedding Etiquette" (Stewart, Tabori & Chang; 2008). "On the wedding day, if the issue can't be corrected on-site, ask your photographer to be sure to document the centerpieces," she says. "Then let it go, and enjoy the happiest day of your life!" You wouldn't want an argument to cast a pall on the rest of the occasion. You can lodge your complaint and attempt to get a refund -- once you've returned from your honeymoon and have your photo evidence in hand.

Whether you avoid animal products, alcohol, carbs, or anything else, "your wedding is not the time to try to convert people to your way of living," says Mac Adam. The trick is to be true to your beliefs without making guests feel deprived. For example, rather than serving seitan, tofu, or other unfamiliar foods, consider a non-meat pasta. Or offer a choice of vegetarian and non-vegetarian entrees.

Mac Adam recalls one bride whose parents wanted to serve a kosher meal, although only a handful of guests required it. The bride hired a second, kosher caterer to prepare that food. "There is usually some sort of middle ground," Mac Adam says.