Just one in 15 (6.5%) pupils starting secondary school in England "behind" for their age goes on to get five good GCSEs including English and maths, official data shows.
Only a third (34%) of these children achieve the government's benchmark of five GCSEs – or equivalent qualifications – graded A* to C, including English and maths.
NUT general secretary Christine Blower said the social inequalities with which children start school, widen as they progress through their education.
"Instead of focusing on changing school structures and on the pointless naming and shaming of schools, the Government should be ensuring that all schools have the resources and support they need for all pupils to reach their full potential."
In total, 158 schools see 100% of pupils getting five GCSEs A*-C or equivalent, including maths and English.
When the average point score per pupil is used to rank these top performers schools, Lawrence Sheriff Grammar School in Rugby comes top.
Head teacher Dr Peter Kent said much of the school's success was down to Key Stage 4 being spread over three years rather than the traditional two.
"This gives departments a chance to deliver a very personalised curriculum and we all respond well to something that's been tailored to our individual needs," he said.
The poorest performing school was St Aldhelm's Academy in Poole, Dorset, where just 3% of pupils got five GCSEs A*-C or equivalent, including maths and English.
Principal Cheryl Heron, who took over in September 2010, said the results were "disappointing but not unexpected". It would take time to change and transform pupils' learning experiences, she added.
At sixth form level, the Colchester Royal Grammar School in Essex comes out as the best performer, with an average point score per pupil of over 1,477 – this is the equivalent of over four A*s and one A grade at A-level.
The best performing county was Sutton in London, where 74.7% of pupils got the government benchmark of five GCSEs, including maths and English. The worst was Knowsley, Merseyside, where 40.8% of pupils reached this level. A Knowsley spokesman said its schools were improving year after year.