Kansas Big Brothers Big Sisters Serving Riley County Since 1904, Big Brothers Big Sisters has operated under the belief that inherent in every child is incredible potential. As the nation’s largest donor- and volunteer-supported mentoring network, Big Brothers Big Sisters makes meaningful, monitored matches between adult volunteers ("Bigs") and children ("Littles"), ages 5 through young adulthood in communities across the country. We develop positive relationships that have a direct and lasting effect on the lives of young people.