Volunteers come from many sources, but most can be categorized in one of two ways.

Affiliated Volunteers are those who are attached to a recognized voluntary or nonprofit organization and are trained for specific disaster response activities. Their relationship with the organization precedes the immediate incident, and they are invited by that organization to become involved in a specific aspect of emergency management. The organization is responsible for training, deploying, assigning, ensuring safety, evaluating, and demobilizing its volunteers.

Unaffiliated Volunteers, also known as spontaneous volunteers, are individuals who offer to help or self-deploy to assist in emergency situations without fully coordinating their activities. They are considered “unaffiliated” in that they are not part of a disaster relief organization. Although unaffiliated volunteers can be significant resources, verifying their training or credentials and matching them with the appropriate services can be difficult.