Franklin Roosevelt called it the most important piece of New Deal legislation following the Social Security Act.
In addition to establishing overtime pay, it also established the minimum wage, the 8 hour day and the 40 hour work week. It also placed age limits on work, thereby ensuring that kids under 16 went to school primarily - not a job site.
For more detail:
- United States Department of Labor: Fair Labor Standards Act of 1938: Maximum Struggle for a Minimum Wage.
- US History: Fair Labor Standards Act.
- Legislative History of the Fair Labor Standards Act.
- Wikipedia: Fair Labor Standards Act.
- US Code: Fair Labor Standards Act.
Interesting Trivia: The law was originally written by Hugo Black when he was a Senator from Alabama. He would later be appointed to the Supreme Court in 1937 and would serve until 1971.