The No Child Left Behind Act (NCLB) has made substantial changes to the Elementary and Secondary Education Act (ESEA). These changes range from new assessment and accountability provisions in Title I that affect states, school districts, and schools to increased flexibility in use of funds for several programs, including the ability to consolidate funds from certain programs at both state and local levels. Implementing these changes poses difficult challenges for school officials at all levels. The purpose of this paper is to help educational leaders in Arkansas, Louisiana, New Mexico, Oklahoma, and Texas gain increased knowledge of these challenges through increased understanding of the main changes in the law, and of the current situation in the states concerning the new provisions. The scope of the NCLB covers many programs and topics, and contains themes including standards, assessment, and accountability; improving teacher quality; increasing options for parents; flexibility for states, school districts, and schools; and increased attention to literacy. This paper is organized around these themes, along with the use of scientifically based research. Two appendices contain definitions of "highly qualified teacher" and "scientifically based research." (RT)