The author reports the finding of a study released by the National Research Council, which is an arm of the National Academies, a scientific body created to advise the federal government on scientific matters. After six years of study, a national panel of prominent scholars has concluded that teachers from alternative programs appear no worse--or better--than those from traditional college-based preparation programs. Studies commissioned by the committee and others show that differences among various alternative-certification programs are often as great as those between alternative programs and the traditional ones. The report adds that a more fruitful line of research is to compare particular aspects of such programs, such as the timing of students' field experiences, the level of teachers' content knowledge, or program selectivity, and how they affect K-12 students' learning. According to the panel, the lack of solid evidence to answer the perennial debate over alternative-certification vs. traditional college-based programs reflects the generally thin research base in the field over how best to prepare the nation's 3.8 million teachers. A growing body of evidence suggests that teachers are the single most important school-based influence on children's learning. Yet experts disagree on the best way to train the estimated 200,000 people who complete some sort of U.S. teacher-preparation program each year, according to the report from the Committee on the Study of Teacher Education Programs.