Many children's choirs are started to serve a cause. Create a children's choir that hosts events which raise money for events, such as children's charities. Your choir can also perform for nursing homes, hospitals and in underserved communities. For a choir of this sort, advertise for auditions or recruit in nearby schools and religious organizations. Call the schools or religious organizations and ask if you can put your advertisement on one of their announcement boards.
Many children in economically disadvantaged areas do not participate in after school activities. However, a choir can provide an amazing outlet for their creative energy. If you work at a school, propose a choir class or a club that can meet before or after school. Teach children the basics of singing and educate them about different genres and styles of music. Pick easy songs at first, but progress as students become more advanced.
Many religious organizations and places of worship have children's choirs as part of their outreach mission. Depending on the schedule of the church or temple, you can hold a children's choir during worship or as a separate program altogether. Make several announcements during worship about your wish to start a children's choir and hold a meeting for interested children. Your choir can perform concerts for the religious organization or place of worship, perform in worship services or even create their own children's worship.
Many neighborhoods or apartment buildings house large numbers of children within its confines. Create a choir, if there is enough interest, to perform for the neighborhood or the community. Call up your neighborhood council or print out fliers and put them on doors or in mailboxes. Have the children meet a few times a week to rehearse songs together.