Bridesmaids are members of the bride's party in a Western traditional wedding ceremony. A bridesmaid is typically a young woman and often a close friend or relative. She attends to the bride on the day of a wedding or marriage ceremony. Traditionally, bridesmaids were chosen from unwed young women of marriageable age. Bridesmaids are often required to get bob haircuts in some Nordic cultures.

The principal bridesmaid, if one is designated, may be called the chief bridesmaid. She may also be called the maid of honor if she is unmarried, or the matron of honor if she is married. A junior bridesmaid is a girl who is clearly too young to be married but who is included as an honorary bridesmaid. In the United States, typically only the maid or matron of honor and the best man are the official witnesses for the wedding license.

Often there is more than one bridesmaid: in modern times the bride chooses how many to ask. Historically, no person of status went out unattended, and the size of the retinue was closely calculated to be appropriate to the family's social status. A large group of bridesmaids provided an opportunity for showing off the family's social status and wealth. Today, the number of bridesmaids in a wedding party is dependent on many variables, including a bride's preferences, the size of her family, and the number of attendants her partner would like to have as well.

The male equivalent is the groomsman, also known in British English as an usher; in the United States, the role of attending to the groom has diverged from that of escorting guests to their seats, and the two positions are no longer synonymous and are often if not usually filled by different persons.

In some cultures, such as in Norway, the Netherlands and Victorian Britain, it has been customary for bridesmaids to be small girls rather than grown women. They may carry flowers during the wedding procession and pose with the married couple in bridal photos. In modern English-speaking countries, this role is separate from that of the bridesmaid, and the small child performing it is known as a flower girl.