A child's chances of attending a weaker school may depend on where they live, according to research.
A study has found that the likelihood of attending a school rated "satisfactory" is different in various parts of the country.
It also concludes that children from poorer families are more likely to be taught in weaker schools.
The study, by the think-tank RSA, used data from schools inspectorate Ofsted to examine the make-up and location of schools judged to be satisfactory.
Certain parts of England have higher proportions of satisfactory schools, the researchers found, with the East Midlands, Yorkshire and the East of England having the greatest numbers.
North East Lincolnshire has the highest according to the research at 83%, with Blackpool, Merton Peterborough, Kingston upon Hull and Bradford all with above 60%. It also found that half (50%) of all satisfactory schools remain satisfactory at their next inspection, while 8% then fall to become inadequate.
But while just over half (52%) of satisfactory schools teaching richer pupils improved their rating, the same was true for only 36% of those serving the poorest youngsters.
RSA director of education Professor Becky Francis said: "Given the larger proportion of 'satisfactory' schools compared to failing schools, they are having a more widespread impact on outcomes for disadvantaged children than are failing schools. It's really urgent that this issue be addressed."
The report comes just weeks after Ofsted's annual report suggested that many schools are coasting, with around one in seven remaining "stubbornly" satisfactory, with little prospect of improvement.
Schools Minister Nick Gibb said: "No school can ever afford to rest on its laurels or be complacent. Pupils' time at school is short so they suffer if heads don't strive to drive up standards year after year. We will not let mediocre performance continue unchecked and we are clear that there will be no hiding place for schools that are not making the progress they should."