The gap between the best and worst performing pupils in Scotland is growing, an official report has found.
Inspectors urged schools to spot weaker pupils quickly
Schools inspectors highlighted the problem, despite ministers spending an unprecedented £19bn on education since Scottish devolution.
Their report also found a widening gap in primary schools in benchmark reading, writing and maths standards.
The Tories branded it "depressing" while the education minister said "decisive" action was being taken.
As much as £62m has been targeted at deprived areas, with the aim of breaking the link between poverty and under-achievement.
Funding for schools has risen by about 50% in the last eight years.
In primary schools alone, spending has gone up 9% in a single year to just under £4,000 for each child - while in secondary schools the figure is £5,500.
Research has shown that if pupils failed to land a job or a place at college by the age of 21, young men were three times more likely to have poor mental health and five times more likely to have a criminal record.
Officials from Her Majesty's Inspectorate of Education (HMIE) Scotland urged schools to identify the weakest pupils early and take quick and consistent action, accepting nothing but the best from youngsters.
They said more help was needed for the lowest performing 20% of pupils.
Figures for reading, writing and maths in the five to 14 age band showed the proportion of pupils who had not reached the expected level was falling.
As much as £62m has been targeted at deprived pupils
However, the proportion who were doing better than the expected level was rising at a faster rate, meaning that the gap between the two groups was slowly increasing.
In addition, while the average performance of high achievers at S4 level was gradually increasing - figures for the lowest performing fifth had remained constant in recent years.
The study, Missing Out, suggested ministers had their work cut out in their drive to make sure every youngster left school "with the maximum level of skills and qualifications possible".
Findings stressed there should be better communication and "partnership working" to ensure prompt and effective support for youngsters and their families.
HMIE Senior Chief Inspector Graham Donaldson said: "In school education we have paid too little attention to the lowest-performing 20% of pupils.
"We need to look closely at how everyone involved in education can make a difference to these young people's educational experience."
However, he praised headteachers who, for instance, challenged pupils' behaviour and introduced schemes such homework clubs and Easter classes.
Ministers, who launched a Closing the Opportunity Gap policy, have set an ambitious target of every 19-year-old being in education, training or work.
Annabel Goldie, leader of the Scottish Conservative Party, said the report highlighted a "depressing and worrying situation".
She praised Mr McConnell for recognising the importance of headteacher leadership and parental involvement in schools.
But she added: "Why has this executive for six years followed a programme precisely designed to undermine the freedom of headteachers and parental involvement in schools by interfering with the rights of headteachers to exclude disruptive pupils and by proposing to abolish school boards?"
She urged Mr McConnell during First Minister's Questions (FMQs) to give headteachers and parents greater freedom to run schools.
"The Scottish Executive is damaging the very things that can help make schools a success," she said.
Mr McConnell countered: "Headteachers have the power to exclude pupils and they should use it whenever they feel they have to."
Education Minister Peter Peacock said the watchdogs' findings were further evidence poverty was one of the major factors which contributed to pupils' poor performance.
However, he added: "It will take a generation or more to fix but we are acting now and we are acting decisively.
"We will tackle why it is some schools are able to successfully raise attainment in our poorest communities and others are being less successful."