The federal No Child Left Behind Act of 2001 requires that by the end of the 2005-06 school year, every teacher working in a public school must be “highly qualified”—meaning that a teacher is certified and has demonstrated proficiency in his or her subject matter, by having majored in the subject in college, passing a subject-knowledge test, or obtaining advanced certification in the subject. The law also calls for strengthening teacher preparation and professional development services.