Of all their duties, the bride's parents' role as host and hostess of the reception is foremost. This honor is theirs because traditionally they pay for part, if not all, of the festivities. As such, their names have historically gone at the top of the invitations, and they play a special role at the reception of making guests feel welcome and ensuring that everything runs smoothly.
This also means it falls on the parents of the bride to determine, roughly, the guest count and to allot fair portions of this total to the groom's parents. Because the final head count essentially comes down to expense -- which can be a sensitive topic -- clear and considerate communication between both families is essential.
Of course, in many cases, paying and being hosts means that the parents of the bride want certain things done their way. Parents have been known to insist that the location, date, or menu of a wedding meets their specifications -- or at least accommodates their interests. Ideally, compromises are reached that everyone can live with: The reception menu includes dishes for vegetarians as well as meat eaters, and the seaside location features a sheltered indoor space with comfortable seats for guests who don't care to stroll barefoot on the sand.
But frequently, the "paying versus influence" issue requires a delicate balancing act on the part of the couple, especially now that more and more couples are sharing wedding expenses with the bride's parents. Even when the bride's parents don't contribute financially to the reception, they may still be called upon to act as cohosts, and many brides and grooms find they appreciate this gracious help during the celebration.
Long before they take their turns as host and hostess, the parents of the bride have duties to attend to, beginning with sending the engagement announcements to the local newspapers. If the groom is from another town or if his parents live farther than a local paper away, the bride's parents should find out whether they would like the announcement to appear in their hometown paper as well.
Once plans are afoot, things can get very busy for the parents of the bride -- particularly her mother. This is especially true if a bride no longer lives in her hometown but plans to marry there, because it is usually her mother who becomes the unofficial wedding consultant for the upcoming production. The mother of the bride also typically helps the bride with coordinating the invitations, and the ceremony and reception details -- offering as much or as little advice and assistance as her daughter requests.
She is also a good person to act as the liaison among the different parties involved in the planning. Particularly useful are her updates with the groom's family, which can also help both sides forge closer ties before the event. As for the wedding-day outfits for the mothers of the bride and groom, historically, the first pick has gone to the mother of the bride, who in turn informs the mother of the groom of the color and style of her selection. The idea is that the groom's mother will not choose a color that clashes or a style that seems to outshine the bride's mom.
The father of the bride has fewer designated tasks, which makes him available to step in and save the day whenever his daughter or wife needs him. Besides his duties as host, which may include a stint in the receiving line (though this is optional for the fathers of both bride and groom) and a welcome toast at the reception, his next most high-profile assignment is to escort his daughter on her last walk as a single woman. (In Jewish ceremonies, this honor goes to both parents.)
During the wedding reception, the father's duties also call for him to dance with his daughter, keep an eye on the food and drink supplies, and write last-minute checks to suppliers and vendors. Finally, the parents of the bride should aim to be the last to leave the reception, perhaps making arrangements for gifts to be taken to the new couple's home, and generally overseeing the winding down and closing out of the party.
Like the bride's parents, the groom's mother and father have duties that begin as soon as the engagement is announced. Traditionally, it is the groom's parents who reach out to the bride's to introduce themselves if they haven't already met, share formal congratulations, and try to arrange an in-person visit, if it's feasible. If they haven't had the opportunity to congratulate the bride in person, a warm, welcoming note is also in order.
While they do not mastermind the biggest party, the groom's mother and father do get to throw a few of their own. At the outset, some parents choose to host an engagement party for their son and his intended, for the express purpose of welcoming her and introducing her to their friends and extended family. Although this isn't a requirement, it can be a wonderful way of getting future wedding guests together to establish a rapport before the event -- familiar faces always make for a more convivial affair.
The groom's father can also have a hand in planning the bachelor party, if he chooses to. And, of course, both the groom's parents traditionally organize (and pay for) the rehearsal dinner. This can range in size from a small occasion for members of the wedding party only to a grand soiree (never to outdo the wedding, of course) that includes half or more of the wedding guests.
A final word on costs: There are many expenses that usually fall to the groom, such as the marriage license, flowers for the women of the wedding party and the mothers, clergy fees, and the honeymoon. Although it is not at all an obligation for them, his parents might decide to assist him with any of these.