Under the federal law, students at all public schools are expected to become "proficient"--as defined by each state--by the end of 2013-14 school year. The law requires steady academic progress overall and by subgroups of students, such as poor and minority youngsters. The law dishes out increasingly tough consequences for Title I schools that continually fail to make adequate yearly progress. They range from compelling districts to spend a portion of their federal aid on allowing students to transfer from low-performing schools to restructuring a school if it fails to improve over several years. The mandate of 95 percent participation in state tests was aimed at ensuring that schools' performance was accurately measured. This article reports on the problems faced by schools that have trouble administering the participation mandate.