A year ago, Arne Duncan was known as a long-serving urban district chief who had used his collegial management style to push innovation and close failing schools in Chicago. This week, he enters his second year as U.S. secretary of education pursuing a similar national policy agenda that could place him among the most influential leaders in his department's 30-year history. Empowered by up to $100 billion in economic-stimulus aid for education--and the support of President Barack Obama, whom he has long known--Mr. Duncan has pressed hard on such priorities as charter schools, teacher performance pay, common academic standards, and turnarounds of low-performing schools. He has used his bully pulpit to assess blame for a K-12 system he sees as marred by mediocre student performance, dismal graduation rates in some cities, and stubborn achievement gaps between minority and white students. Observers are now watching to see whether Mr. Duncan will succeed in codifying the administration's agenda through the renewal of the Elementary and Secondary Education Act, last revised eight years ago as the No Child Left Behind law. And as the American Recovery and Reinvestment Act enters its second and final year, Mr. Duncan is expected to continue wielding the leverage that the stimulus law's nearly $10 billion in competitive-grant programs for education gives him. Already, he has held out the prospect of $4 billion in Race to the Top Fund grants to persuade states to lift their caps on charter schools and to ease the way for teacher merit-pay programs. He has told states and school districts receiving $3 billion in Title I School Improvement Grants that they must take "dramatic" steps to fix the worst schools, such as shutting them down. And he's using a $650 million Investing in Innovation Fund to spur districts to partner with the private sector in making reforms. With such exposure--and money--comes criticism from different directions. Officials in a number of states and in Congress object to what they view as overly prescriptive mandates for fixing schools. Yet even people who don't like Mr. Duncan's priorities say he's been skillful at advancing them.