Once a passionate advocate for injecting greater competition and accountability into the U.S. education system, the New York University scholar Diane Ravitch realized three years ago that her views had evolved to a point where she was contradicting herself on a regular basis. Like any good historian, she decided to set the record straight. Her newest book, "The Death and Life of the Great American School System: How Testing and Choice Are Undermining Education," which was published last week by Basic Books, is the result of that effort. In 308 pages, it lays out the reasons for Ms. Ravitch's about-face on charter schools, school choice, and other market-oriented reform strategies in education, and explains why she no longer supports the federal No Child Left Behind Act and other endeavors designed to hold schools and teachers accountable for their students' test results. Along the way, the book also skewers much of President Barack Obama's agenda for improving the nation's schools; the recent involvement in the field of major foundations, including the Seattle-based Bill & Melinda Gates Foundation; vaunted school improvement efforts in New York City and elsewhere; and the growing emphasis on using test-score data to guide educational decision making. Because it's not often that the field's most influential thinkers publicly reverse themselves, Ms. Ravitch's book started attracting attention from major news organizations, prominent educators, and influential think tanks even before its official publication date. Ms. Ravitch established her credentials as a conservative voice on education as far back as 1978, with the publication of her second book, "The Revisionists Revised." In it, she critiqued what she called "radical attacks" on education from the left. In the nearly 20 other books she has written, co-written, or edited over the years, she has also weighed in against progressive education and attempts on both the left and the right to make textbooks and standardized tests "politically correct." In reality, though, Ms. Ravitch has always been more complex in her views than her passionate, sometimes acerbic writings might suggest. The writer was a Democrat when she served in the first Bush administration, and her former husband, Richard Ravitch, a veteran mover and shaker in Democratic circles, is now the lieutenant governor of New York.