There is a target for an annual increase in GCSE results at A* to C
Hundreds of thousands of students are receiving their GCSE exam results in England, Wales and Northern Ireland.
It is thought that the trend for higher pass rates and more entries being awarded the top grades will continue.
Ministers say over 30% of pupils must get five A*-C grades, including maths and English, by 2011.
The results for the 638 schools in England branded as under-performing in the government's "National Challenge" programme will be keenly watched.
Dr John Dunford, general secretary of the Association of School and College Leaders (ASCL) says the programme has put extra pressure on schools.
He also warned against judging schools on one year's results.
"The GCSE results are most significant for the pupils themselves," he said.
"We have got to be reasonable because it takes time to turn schools around."
The data being released later on Thursday, by the exam boards collectively, will not be in the form of school-by-school breakdowns - though some schools will release their results individually.
The statistics relate to the numbers of entries for various subjects and the grades awarded.
Separate results are available for England, Wales and Northern Ireland. Scotland's exam results were released two weeks ago.
For pupils who do not make the grade, the message from the government will be "Don't give up".
From 2013, everyone will be expected to keep learning in school, college or at work up to the age of 17. From 2015, the "leaving age" will be 18.
Education minister Lord Adonis said: "Young people will be getting the results that their hard work deserves and most will be inspired to stay in education or training. But those that don't do as well as expected should not give up.
"The September Guarantee means that all those completing year 11 are guaranteed, by the end of September, the offer of a suitable opportunity to stay in learning - regardless of their results."
The Conservatives say there is a "long tail of educational underachievement", with tens of thousands of children leaving school each year without any good GCSE passes.
They say that since 1997, more than two million children have left school without a single GCSE at grade C or above.
Statistics on the proportion of 15-year-old pupils achieving five or more grades A* to C will be available in a couple of months.
In England, confirmed details of individual schools' performances are published each January.