Robert is a month shy of his fifth birthday, and a fistfight away from being expelled from junior kindergarten.

He trips, pinches and punches, and his teacher complains that he cannot work in a team or even on his own for very long. He is smart -- a recent test put his IQ at 148 -- but he is in danger of falling behind. One more misstep, his private school has warned, and he's gone. (At least until he is required to show up somewhere for class this fall.

"We thought he was just being boyish," says his mother.

"Imagine," sighs his father. "Expelled from junior K."

Educators see kids like Robert all the time: An estimated one in four children show up on that first day of school, short on the basic tools they need to succeed, from simple language to fine motor skills to co-operating with classmates.

Study after study shows that children who do not arrive "ready to learn" fall behind, are rejected by peers and sour on school, setting them on high-risk paths toward unhealthy, unhappy adulthoods.

Robert's troubles come as a shock to his attentive parents, a pair of PhDs with good jobs, a house full of books and a playroom cluttered with toys. If anything, they have been too doting on their firstborn. (They spoke only on the condition that their son's real name not be used.)

Until recently, even experts assumed that children headed for problems were easy to spot: They came from poor backgrounds, the offspring of drug addicts and alcoholics, abused and neglected by their parents.

It is just not that simple, and recent findings have bolstered criticism of Canada's early childhood policy, which has largely targeted low-income families.

Yes, money matters: Children who grow up in poverty are more likely to arrive unprepared for school than their financially better-off counterparts. But in real numbers, more than 60 per cent of vulnerable children in Canada are more thinly spread throughout the middle classes of the country, in families that look a lot like Robert's. They show up in comfortable two-parent homes, awash in Fisher Price and Playmobil, the brothers and sisters to scholastic stars.

A national study of 22,000 children from birth to age 11, using parental surveys and home visits, found that 37 per cent of children in the poorest families were vulnerable on one or more skill sets: They had difficult temperaments, limited communications skills or below-average physical abilities.

But even among Canada's wealthiest families -- the top quarter of earners -- almost one in four children (24 per cent) were also flagged with problems.

A second study evaluated every kindergarten student in the city of Vancouver and reached the same conclusion: True, the proportion of children with school-readiness shortfalls increased dramatically as one moved from the most affluent west-side neighbourhoods to the poorest east-end parts of the city. But the largest number of vulnerable children were spread through the city's middle-class sections.

"This is a vitally important story," said Clyde Hertzman, the University of British Columbia researcher who is now mapping the entire province. "The numbers game [says] that if you concentrate all your energy in the least-advantaged group, then you miss the majority of kids who are developmentally delayed. These are issues that apply, one way or another, across society."

Jim Grieves, the director of education for the Peel School Board, remembers from his days as a school principal the students who arrived in designer clothes but without consistent parental support. Now, when he presents the statistics to middle-class audiences, their first reaction is to "rail against" them.

"We're raised on the notion that if you have money and advantage, you can pretty much assume everything will turn out fine," he said. "But then they assess the pace of life, and the way they are struggling to maintain even middle-class status, and they see there are lots of holes in the way we are raising our children. It's pretty scary, actually."

Of course, the majority of children in Canada are raised in middle-class families, so it might seem natural that most of the children at risk would come from their ranks. But the findings toppled a long-standing hypothesis. Experts and government officials expected to find a mass of children with problems clustered among poor Canadians, and the offspring of the middle class doing fine and looking pretty similar to each other, apart from the luck of genes and IQ.

This was the very theory that Doug Willms, director of the Canadian Research Institute for Social Policy at the University of New Brunswick, was asked by Ottawa to prove. When he began to analyze early data from the National Longitudinal Survey of Children and Youth, he found the cluster was there -- but at the same time, two-thirds of children from families earning less than $25,000 were arriving at school as ready to learn as their wealthiest peers.

Either something was protecting them from the effect of income, or income was not as significant a factor as previously believed.

As it turns out, both are true.

Childhood troubles, current research suggests, work like heart disease: The less money you have, the more likely you are to have them. The impact of income and parental education on school performance in Canada falls between those of the Scandinavian countries (with their comprehensive early-childhood programs) and of the United States, where a wider gulf exists between rich and poor -- although there is evidence that the gap here is growing rather than shrinking.

When testing preschoolers on what words they understand ("receptive vocabulary"), Dr. Willms found that, on average, children raised in the second-lowest income bracket scored about nine points lower than children in the second highest. Even so, the majority of children who scored below average were from middle and upper-middle class families, and many low-income children scored above average.

There was no magical social-economic status by which a child's readiness for kindergarten was guaranteed -- although for every $10,000 a family's income increased, the percentage of vulnerable children declined somewhat, even between the two wealthiest groups of families.

On the other side of country, Dr. Hertzman began collecting anonymous data on every kindergarten student in British Columbia using the Early Development Instrument, a program that allows teachers to score their students on a broad range of cognitive and behavioural measures.

He then mapped out the location of students based on their scores. Across the province, neighbourhood income, and even parental education, wasn't always a consistent marker of success. Overall, for instance, a higher proportion of children in the resort community of Whistler were vulnerable in their development than those in several neighbourhoods in the working-class sawmill town of Squamish, where the median family income is $10,000 less and half as many parenting-aged adults have a university degree. A smaller proportion of kindergarten children were vulnerable in the city of Vernon than in Kelowna, despite lower education rates and family earnings.

This is because, Dr. Hertzman says, most children are shaped not by major events or clear deficiencies in their upbringing, but by more subtle day-to-day circumstances.

In the same way that parents can make major differences in development by doing simple things like chatting a lot with their children, a series of small negatives can leave larger hurts.

What makes kids vulnerable in middle-class homes? Dr. Hertzman has a long list: Maybe their siblings mistreat them when the parents are away; maybe their boring nanny does nothing but babysit; maybe their parents are too strict and inflexible, or too permissive and indulgent, or working all the time; maybe their working parents are too tired to read to them each night; maybe their families are socially isolated from other relatives and adults who may understand the children better; maybe their neighbours, though middle class, aren't all that neighbourly.

Consider, Dr. Hertzman suggests, family homes where parents can see the backyards from their kitchen windows.

"That could make the difference for one kid to get all sorts of chance to go out and play and blow off steam, and also develop all those muscle groups and cerebellum connections that cross-fertilize into math skills, versus the kid who doesn't."

To take another example, even in the least transient, wealthier neighbourhoods, fewer than 20 per cent of the children born in one Vancouver area were still living there by the time they turned 9. For most children now, Dr. Hertzman says, the connection to their neighbourhoods and the constancy of their friendships -- both boons to development -- tend to be much diminished from what their parents experienced in a past, less-mobile time.

Many researchers believe the neighbourhood plays a key role. In Saskatoon, one study found that children were doing extremely well in a lower-income area where the parents were employed and less likely to move. In that part of the city, said University of Saskatchewan researcher Nazeem Muhajarine, parents could count on their neighbours to watch out for their children.

"It affects how people interact with each other on the street, and at the grocery story," he said

When you're a preschooler, your neighbourhood is your world. So the increasing stratification of Canadian cities is worrisome, researchers say, particularly for young children.

In Vancouver, for instance, Dr Hertzman found that low-income children who lived in mixed-income neighbourhoods did better in kindergarten than those living in poorer places (and their presence didn't hurt the performance of their higher-income peers).

The science shows, Dr. Hertzman says, why Canada's piecemeal policies, aimed largely at boosting incomes for poor families, make little progress compared to nations like Sweden and France, with their programs of universally subsidized childcare, family allowances, parental leaves and parenting courses. When he gives presentations around the province, he points to empty classrooms in neighbourhood schools that could be transformed into daycare centres and sites for parenting lectures and family literacy training -- offering individual help while fostering community.

Targeted programs are cheaper and often reach those most in need, but can stigmatize parents. And they can be too narrowly focused to change the overall environment for a child. Universal programs are costly, and need to be designed so that poorer families can access them; one recent study found that more than half of the subsidized daycare spots in Quebec were filled with families earning at least $65,000 a year.

Middle-class parents tend to be more efficient advocates for their children when problems arise, assuming the problems are found early enough -- even by the early school years, solutions become more difficult and expensive.

Robert's parents, for their part, eventually hired a psychologist, developed a new at-home parenting plan to encourage his independence, and negotiated an arrangement with the school to extend their son's probation. This included bumping him up to senior kindergarten early, to give him more of a challenge.

"Parenting is not always intuitive," says Robert's mother. "Mostly you are just responding to the things as they happen. It would be nice to have more tools."

That's true regardless of family income, and is the reason why many researchers in the field make the case for a combination of targeted and universal programs, including a play-based, full-day preschool curriculum, reciting the benefits reported in Western European countries that have adopted this system.

But Canadian parents are split on the question, as evinced by the recent debate in Alberta over junior kindergarten; in a Globe and Mail poll of 700 parents conducted by Ipsos-Reid, less than half thought that day-long programs starting with three-year-olds was a good idea.

"We hang on to the notion that kids should be at home," says Pat Dickinson, a former literacy co-ordinator for the Halton, Ont., region -- "even though nobody is at home."

Those pushing a more universal approach to early childhood development have a convert in David Dodge, the Governor of the Bank of Canada. He recently defined to an audience of early-childhood experts the economic case for spending more money on the youngest citizens, where the nation would see a larger return on investment.

But Canada, he said, does the opposite: It spends more public funds on post-secondary education, while leaving families to spend more privately in the early years. Given that a small cohort of children will eventually have to support a larger group of retiring baby boomers, he said that it is even more important each one of them become as productive as possible.

"The real challenge," Dr. Dodge said, "is not delivering bigger cheques to poor families, it is how to reach all parents in their communities.

Income vs. learning

The prevalence of vulnerable children (aged 4-11) by family income in 1998-99:

Below $33,400: 29.5%

$33,401-$52,500: 25.8%

$52,501-$77,500: 23.5%

Over $77,000: 18.5%

Vulnerable children had either poor learning outcomes or behaviour problems, reducing their chances of leading healthy and productive lives.

SOURCE: DOUGLAS WILLMS, VULNERABLE CHILDREN (U OF A PRESS)