Reforms that aim to give children and young people with special educational needs (SEN) and their parents a greater say in the support they receive have come into effect in England.
Under the "simpler and more joined up" system stretching from birth to age 25, "education, health and care plans" replace special needs statements.
The government said it was "a landmark moment" for children with SEN.
Parents can now express a preference for a greater range of schools.
Up to now, the parents of a child with a special educational needs had to ask the local education authority to complete an assessment. The most severe cases received a special needs statement, a formal document outlining the child's learning difficulties and support to be given, which was enforceable by law.
The new system incorporates health and care needs alongside educational ones, with an individual worker and single budget for each family.
The changes were set out in the Children and Families Act, which became law in March.
Children and families minister Edward Timpson said the reforms "put children and parents at the heart of the system".
"For too long, families have found themselves battling against a complex and fragmented system," he said.
"These reforms ensure support fits in with their needs and not the other way round - they will result in a simpler and more joined up system that focuses on children achieving their best.
"This is the beginning of a journey and the vast majority of local authorities have told us they are ready and parents have been supportive over the changes."
A new legal right lets those with an education, health and care statement express a preference to attend an academy, free school or further education college.
Mainstream or special schools were the only previous options.
Councils must now publish a "local offer" outlining the support available to all children and young people with disabilities and their families.
And the reforms have introduced mediation for disputes with local authorities as well as a trial of a new appeals system for those who are unhappy with the support they have received.
In April, two charities complained the changes were being implemented too quickly.
The National Autistic Society said details of "the biggest reform of the SEN system in 30 years" had not been finalised at that time.
And learning disability Mencap also complained that "the finer details" had yet to be published, "which means that professionals who work with children and young people with SEN have just a few months' notice of their new obligations before they are expected to meet them".
At the time, the government said the system would allow change to "take place gradually".