As part of the Ticket to Work and Work Incentives Improvement Act of 1999, Congress asked the Social Security Administration to conduct the Benefit Offset National Demonstration (BOND). BOND tests alternative Social Security Disability Insurance (SSDI) work rules that increase the incentive for SSDI beneficiaries to return to work. Benefits are reduced gradually when a beneficiary has earnings exceeding a specific amount, instead of being cut to $0 (as under current law). As a subcontractor to Abt Associates, Mathematica provides implementation support and co-leads the evaluation. This is the first evaluation report on Stage 1, which involved implementing benefit offset rules for a random, nationally representative sample.