Big Brothers Big Sisters is the oldest, largest and most effective youth mentoring organization in the United States. We have been the leader in one-to-one youth service for more than a century, developing positive relationships that have a direct and lasting impact on the lives of young people. Big Brothers Big Sisters of Flint and Genesee County serves local children ages 6 through 18. The Big Brothers Big Sisters Mission is to help children reach their potential through professionally supported, one-to-one relationships with measurable impact.