The mother of the bride is the official hostess of the reception. It's your job, along with other important family members, to greet and welcome guests.
As head of the receiving line, try to set a tempo that keeps guests moving quickly into the reception hall. Assemble the receiving party so that each member makes warm, brief greetings, handing the guest off to the next person. The last greeter should direct guests to food or beverages.
Once the party starts, you may be called upon to dance with the bride's father or her new husband. But your most important responsibility of the day is to enjoy the occasion, congratulating the bride and groom on their beautiful wedding and new life together.