This is the 33rd Annual Report to Congress on the Implementation of the "Individuals with Disabilities Education Act," 2011. Section 664(d) of the "Individuals with Disabilities Education Act" ("IDEA"), as reauthorized in 2004, requires that the Department of Education report annually on the progress made toward the provision of a free appropriate public education to all children with disabilities and the provision of early intervention services to infants and toddlers with disabilities. The 33rd Annual Report to Congress on the Implementation of the "Individuals with Disabilities Education Act," 2011 describes our nation's progress in: (1) providing a free appropriate public education (FAPE) for all children with disabilities; (2) ensuring that the rights of children with disabilities and their parents are protected; (3) assisting states and localities in providing for the education of all children with disabilities, and (4) assessing the effectiveness of efforts to educate children with disabilities. The report focuses on the children and students with disabilities being served under "IDEA," Part C or B, nationally and at the state level. The following are appended: (1) Infants, Toddlers, Children, and Students Served Under "IDEA," by Age Group and State; (2) Developmental Delay Data for Children Ages 3 Through 5 and Students Ages 6 Through 9 Served Under "IDEA," Part B; and (3) Differences in State Reporting of "IDEA," Part B, Disabilities.