The Individuals with Disabilities Education Act (IDEA) provides federal funding for the education of children with disabilities and requires, as a condition for the receipt of such funds, the provision of a free appropriate public education (FAPE) for children with disabilities. The IDEA's predecessor legislation, the Education for All Handicapped Children Act ( P.L. 94-142 , passed in 1975), responded to increased awareness of the need to educate children with disabilities, and to judicial decisions requiring that states provide an education for children with disabilities if they provided an education for children without disabilities. In its current form, the IDEA both authorizes federal funding for special education and related services and, for states that accept these funds, sets out principles under which special education and related services are to be provided. Over the past four decades, the IDEA has been the subject of numerous reauthorizations to extend services and rights to children with disabilities. The most recent reauthorization was P.L. 108-446 in 2004. Funding for IDEA Part B, Assistance for Education of all Children with Disabilities, is permanently authorized. Funding for Part C, Infants and Toddlers with Disabilities, and Part D, National Activities, was authorized through FY2011. Funding for the programs continues to be authorized through annual appropriations. The IDEA consists of four parts. Part A contains the general provisions, including the purposes of the act and definitions. Part B contains provisions relating to the education of school-aged children (the grants-to-states program) and the state grants program for preschool children with disabilities (Section 619). Part C authorizes state grants for programs serving infants and toddlers with disabilities. Part D contains the requirements for various national activities designed to improve the education of children with disabilities. Table 1 shows the structure and funding of the IDEA and is followed by a more detailed discussion of the four parts of the act. Part A includes congressional findings pertinent to the act, the purposes of the act, and definitions. The definitions included in Part A are important in interpreting the requirements of the act. These include, among others, definitions of child with a disability , specific learning disability , free appropriate public education , individualized education pro gram , local educational agency , related services , special education , supplementary aids and services , transition s ervices , and excess costs . Part B provides federal funding to states for the education of children with disabilities and requires, as a condition for the receipt of such funds, the provision of a FAPE to children with disabilities between the ages of 3 and 21. School districts within participating states must identify, locate, and evaluate all children with disabilities, regardless of the severity of their disability, to determine which children are eligible for special education and related services. Each child receiving services must have an Individualized Education Program (IEP), created by an IEP team, delineating the specific special education and related services to be provided to meet his or her needs. The statute also contains procedural safeguards, which are provisions to protect the rights of parents and children with disabilities to ensure the provision of FAPE. Section 619 authorizes grants to states for preschool programs serving children with disabilities ages three to five. Section 619 is a relatively brief section of the law and deals mostly with the state and substate funding formulas for the preschool program grants and state-level activities. The general purpose of Part C is to aid each state in creating and maintaining "a statewide, comprehensive, coordinated, multidisciplinary, interagency system that provides early intervention services for infants and toddlers with disabilities and their families." Services focus on children (and their families) from birth through age two who are experiencing or have a high probability of experiencing "developmental delay" (as defined by the state) with respect to physical, mental, or other capacities. Services are detailed for each child and his or her family in an Individualized Family Service Plan (IFSP). To the maximum extent feasible, services are to be provided in "natural environments," including the home, with other infants and toddlers who are not disabled. States are required to identify a state lead agency, which might be the state educational agency (SEA) but could be other state agencies, to coordinate the system. Part D authorizes competitive grants to improve the education of children with disabilities under three subparts with different areas of emphasis: (1) state personnel development; (2) personnel preparation, technical assistance, model demonstration projects, and dissemination of information; and (3) support to improve results for children. Under Subpart 1, competitive grants are made to SEAs for state personnel development grants to assist SEAs "in reforming and improving their systems for personnel preparation and professional development in early intervention, educational, and transitions services." Under these grants, personnel preparation and development may be provided for special education teachers, regular education teachers, principals, administrators, related services personnel, paraprofessionals, and early intervention personnel serving infants, toddlers, preschoolers, or children with disabilities. Under Subpart 2, competitive grants are made to entities such as SEAs, local education agencies (LEAs), institutions of higher education (IHEs), and nonprofit organizations for personnel development to help ensure that there are adequate numbers of personnel with skills and knowledge needed to help children with disabilities succeed, for technical assistance and dissemination of material based on knowledge gained through research and practice, and for studies and evaluations. Under Subpart 3, competitive grants are made to nonprofit organizations for parent training and information centers, which provide parents of children with disabilities with needed training and information to work with professionals in meeting the early intervention and special education needs of their children. Competitive grants are also made to entities such as SEAs, LEAs, IHEs, and nonprofit organizations for research, development, and other activities that promote the use of technology in providing special education and early intervention services. Part B is the largest part of the IDEA, and it received nearly 95%, $12.7 billion, of the act's total funding in FY2018. Part B's funding is authorized in two different sections. Section 611, which covers children between the ages of 3 and 21 receiving special education and related services in public schools, received $12.3 billion in FY2018. Section 619, which provides supplementary preschool grants for children between the ages of 3 and 5, received $381.1 million in FY2018. In comparison, as is shown in Table 1 , Part C was appropriated $470 million (3.5% of IDEA funding) in FY2018. Less than 2% of the total IDEA funding went to Part D. The IDEA is one of the largest educational programs overseen by the U.S. Department of Education (ED). As Figure 1 displays, from the first year of funding in 1977 until about a decade ago, appropriations for the Part B grants-to-states program had been rising rapidly. In the first 20 years of funding for the Part B program, appropriations increased approximately 470% in constant 2017 dollars. Between the last two reauthorizations of the IDEA in 1997 and 2004, Part B appropriations rose an average of 18% per year in constant dollars. However, Part B funding trends changed after the 2004 reauthorization, and appropriations have fluctuated in the years since. Part B funding reached its highest levels in FY2005 and FY2009, with inflation-adjusted amounts exceeding $13.1 billion each year. In FY2017 the appropriation was $12 billion, and in FY2018 it was $12.3 billion. Despite recent fluctuations in Part B appropriations, funding for the Part B grants-to-states program increased steadily for most of its first four decades ( Figure 1 ). In contrast, funding levels for the two early childhood grant programs, after experiencing substantial growth in earlier periods in program history, have declined in constant dollar amounts in more recent periods. The Part B, Section 619 preschool grants program began with a period of relatively low funding between FY1980 and FY1986 ($25 million to $29 million), followed by a period of rapid escalation in funding between FY1987 ($180 million) and FY1995 ($360 million). The year-to-year escalation in Section 619 funding slowed over the next five years. In FY2000, Section 619 funding reached its highest annual appropriation level in actual dollars ($390 million), and it maintained that appropriation for the next two years. From FY2003 through the present, Section 619 appropriations have fluctuated somewhat in actual dollars and declined in constant dollars. The Section 619 preschool grants program received its highest level of funding in constant FY2017 dollars in FY1995 ($578 million). In FY2018, the Part B, Section 619 preschool grants program was appropriated $381 million. The Part C, infants and families program experienced a period of relatively constant funding growth for its first 15 years; Part C appropriations increased from $50 million in FY1987 to over $444 million in FY2004. In the years since, the IDEA Part C grants program has received relatively level appropriations in actual dollars and declining funding in constant 2017 dollars. Between FY2004, the year of the IDEA's most recent reauthorization, and FY2012, funding in nominal dollars for the Part C program changed relatively little from one year to the next, while funding in inflation-adjusted dollars eroded. For the past five years, appropriations for the Part C program have fluctuated. In FY2018, the Part C, infants and families program was appropriated $470 million. Federal laws concerning children with disabilities date from the early 19 th century, but it was not until the Elementary and Secondary Education Act (ESEA) was reauthorized for the first time in 1966 that the first general federal assistance was provided to states for the education of children with disabilities. The original version of the ESEA, which Congress enacted in 1965 as P.L. 89-10, did not specify assistance for children with disabilities.