Thousands of high school pupils in Scotland failed to reach basic standards in literacy and numeracy this year, according to statistics.
HMIE said 75% of S2 pupils should have attained level E assessment
Figures from most councils, obtained under the Freedom of Information Act, said more than 30% of second year pupils had poor results in reading.
Nearly half failed the standards for writing while six in 10 pupils achieved the basic standard for mathematics.
Cosla said statistics did not give the full picture of attainment.
The local authorities body stressed that the tests were no more than a teaching tool.
Pupils in Glasgow had the lowest pass rates for all subjects, where almost six in 10 pupils failed to achieve the benchmark grade of Level E for writing in 2005.
Other poorly-performing areas were West Dunbartonshire, Clackmannanshire and North Lanarkshire.
HM Inspectorate of Education has said 75% of pupils should have attained Level E assessment by the end of the second year of high school.
Conservative education spokesman Lord James Douglas-Hamilton said the figures showed Scotland's pupils were being failed by the comprehensive model.
"These very poor figures once again illustrate that Scottish education is suffering from too many politicians and bureaucrats running our schools, too few parents being allowed a choice in selecting a school for their child and headteachers not having enough freedom to decide what is best in their own unique school environment for each individual child", he said.
The Scottish National Party blamed social deprivation for the poor results.
Education spokeswoman Fiona Hyslop said: "These statistics don't tell us anything new.
"The problem is that they allow the Scottish Executive to hide behind poverty as their excuse for failing these children."
The figures emerged as Education Minister Peter Peacock said £62m of extra funding for additional teachers would be made available over the coming two years to take fuller account of the impact of social deprivation on schools.
Ronnie Smith, of the teaching union EIS, said the statistics were of little value.
He added: "What matters really is the Standard Grade as those are the results that will determine access to higher education or employment."
The Scottish Executive said it was cutting class sizes and reviewing the curriculum to ensure it remained relevant to boost progress at S2 level.
A spokesman said: "Level E is a challenging test and not one that all pupils will achieve in S2.
"However, attainment is steadily improving year-on-year in Scottish schools."
Cosla's education spokesperson, Councillor Rev Ewan Aitken, said: "It really infuriates me the assumption that, taken on their own, these figures in themselves tell us anything significant about the effectiveness of our schools.
"Every school has its own context, which includes issues such as levels of poverty, levels of support from parents and the community, levels of support from business, transport, the quality of the school building, relative mobility of the cohort and much more."
Rev Aitken added that A-E level tests were designed to assess the progress of individual children, rather than the effectiveness of a school.