The Mass Layoff Statistics (MLS) program collects reports on mass layoff actions that result in workers being separated from their jobs. Monthly mass layoff numbers are from establishments which have at least 50 initial claims for unemployment insurance (UI) filed against them during a 5-week period. Extended mass layoff numbers (issued quarterly) are from a subset of such establishments--where private sector nonfarm employers indicate that 50 or more workers were separated from their jobs for at least 31 days.