Young children are starting nursery school unable to speak and listen properly because of continuous noise and poor conversation at home, an Ofsted report has found.
Constantly switched on televisions, noisy brothers and sisters and raised voices are increasingly hampering children's language skills, it says.
The study, on how the best schools teach children to read, says some schools report spending days or weeks educating parents and improving children's social skills.
In some cases, children arrive at nursery still in nappies and with dummies in their mouths.
It says: "The majority of the schools visited that had nursery classes commented that, increasingly, children joined unprepared for learning and with poor listening and speaking skills.
"Lack of preparation extended to children arriving who had not been toilet-trained and children with dummies in their mouths.
The study found phonics helps every child to read well, but only when it is taught rigorously and consistently.
Evidence shows that the critical time for children to become good readers and writers is between the ages of three and seven, the watchdog said, and the best schools are consistent in giving pupils opportunities to talk and listen to build their vocabulary.
Ofsted chief inspector Christine Gilbert said: "Despite some major initiatives in recent years to raise standards in reading and writing, the levels achieved by many children at the end of primary school fall stubbornly short of what is achievable."
Chris Keates, general-secretary of the NASUWT, the largest teachers' union, said: "I welcome the fact that this report acknowledges the hard work and dedication of teachers. I am also pleased that the report emphasises the importance of letting teachers and headteachers use their professional judgement on the best approaches to learning in the classroom."