Does Child Care Equal Aggressive Behavior?

By Betsy Weaver

In the summer of 2001, the National Institutes of Health study on child care in America – an ongoing study over the past 10 years of 1,300 children, ages 4-1/2 to 5-1/2, in child care – released preliminary findings. There was a storm of controversy about one finding: Children who spend more than 30 hours a week in child care scored higher (17 percent) on a scale of aggression than children who spend 10 hours or less (5 percent). By kindergarten, the gap between these groups had lessened to 19 percent and 9 percent respectively.


While this preliminary finding was what made the headlines, many of the study’s authors were frustrated that a full understanding of this finding, as well as other equally important findings, was lost in the shadow of the headlines. Psychologist Kathleen McCartney, a professor of education at the Harvard Graduate School of Education, was one such researcher. We spoke with McCartney about this study and what parents need to know to put the findings in perspective. Here’s some of what she had to say:

The first round of media coverage presented just a small slice of this study’s findings: the “bad news” – that more hours spent in child care are associated with behavior problems and aggression. The second round of coverage included more findings, but the damage had already been done. The public remembered only “child care = aggressive behavior.”

The connection between hours spent in child care and aggressive behavior is real: 17 percent of young children in child care for more than 30 hours per week scored higher on a scale of aggressive behavior, compared to 5 percent for those who were in care for 10 hours or less per week. In kindergarten, the numbers were 19 percent for those who were in care for more than 30 hours and 9 percent for those in care for 10 hours or less.

But what parents need to know is: What does this finding mean? And, what other important findings came out of this study?


• On the scale that was used to determine aggressive behavior, 17 percent was the norm – meaning that in the normal population of kids, 17 percent have the same scores as those in this study. This context has been lost in the media’s telling of the findings. If you took a sample of individuals reading this article, for example, 17 percent would score in the aggressive range the way the children in the study did.


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