The maid of honor is generally a sister or best friend of the bride. As such, she plays a crucial role in the event planning and assisting the bride. She performs all of the bridesmaid expectations as well as the following:
Generally shops with the bride for wedding dresses and attends fittings. She also usually has a voice in choosing the bridesmaid dresses.
Helps the bride with wedding event planning as the bride needs. Some brides want the MOH to come along to all vendor consultations, others just want someone to bounce ideas off of.
Takes the lead on any bridesmaid group gift to the bride (if applicable) and organizes a bridesmaid luncheon, if the bride chooses to have one.
Serves as the bride's assistant on the wedding day, helping her with everything from lipstick freshening to herding the single ladies for the bouquet toss.
Gives a toast at the wedding reception.
Often plans the events such as bridal showers or bachelorette parties, but is not required, and these duties can be split amongst other bridesmaids and friends.