There are several important points to note about the day care study:

1. The paper has NOT been published or peer reviewed, yet
2. The researcher who reported the results has a known anti-daycare bias
3. The research does not and CANNOT prove causality
4. The "increased" aggressiveness is still entirely normal
5. The research found some areas where day care kids were better off

Followed by a short feminist rant

Here are quotes from the media to back up all these assertions:

1) The paper has NOT been published or peer reviewed, yet.

In fact, the authors haven't even finished analyzing the data!

L.A. Times:

   The most recent findings were presented at a conference last week of the Society for Research and Child Development in Minneapolis. But because the work has not yet been published, it has also not yet been formally critiqued by other experts.
   ...
   Researchers also decided to hold off on publishing their findings because they want to perform more analysis, Clarke-Stewart said. They want to compare, for example, how many of the children who were rated as aggressive by their kindergarten teachers were also found by their mothers and child-care providers to be acting up. And they want to compare researchers' own observations to those of teachers.

Salon:

   NICHD study coauthor Marsha Weinraub, a professor of psychology at Temple University, wrote, "We did not prepare a press release, because this report has not yet been peer reviewed and is not in press in any way. This was a series of reports to conference colleagues, something social scientists do all the time.
   "Generally, however, scientists are pretty circumspect in reporting conference findings," she wrote, "but this week that was not the case. I'm sorry. That was something that was not in my control."
   ...
   In her e-mail Weinraub added, "Certainly, it is premature for anyone, least of all developmental researchers, to interpret the meaning of this finding for public policy in light of the information so far and the complicated issues it raises."

You can read the actual announcement at http://www.srcd.org/pp1.html

Most of the data they reported didn't make the press...

2) The researcher who reported the results has a known anti-daycare bias.

LA Times:

   A week after a high-profile study cast a negative light on child care, researchers--including the study's lead statistician--are sharply questioning whether their controversial work has been misrepresented.
   ...
   [S]everal academics involved in the study said that its conclusion was overstated and that other important findings never reached the public. In the aftermath, a rift has been exposed among the research team, and questions from other experts have caused the researchers to perform additional analysis before formally publishing their findings.
   ...
   "I feel we have been extremely irresponsible, and I'm very sorry the results have been presented in this way," said Margaret Burchinal, the lead statistician on the study, funded by National Institute of Child Health and Human Development. "I'm afraid we have scared parents, especially since most parents in this country [have to work]."

Salon:

   The problem, according to several of Belsky's colleagues, is that Belsky's dire pronouncements are not based on conclusive data, and his identification as a "principal investigator" in the study is just plain wrong.

The Salon article goes on to discuss how Belsky published a paper in 1986 suggesting that "evidence" led him to believe child care psychologically damaged children, although other researchers have complained about his methodology and interpretations of the data.

Sarah Friedman, a psychologist at the NICHD and one of the 13 lead investigators in the study, is quoted saying such things as:

• "[Belsky] is not a lead investigator. I understand that he identifies himself as that, but he is misinforming people and he knows better. It's a problem. He is not telling the whole story and is creating a panic."
• "We have no way in this study to attribute cause and effect. In the case of these findings, there is no way to attribute causality."
• "This is completely unprofessional," concludes Friedman, "but this is what he did and a lot of people in the study are upset with him. He didn't represent the truth, he represented his minority [view]."

3) The research does not and CANNOT prove causality.

Salon:

   [T]he Early Child Care Study is not a controlled experiment but an observational study, which, by definition, does not yield the kind of data that researchers need to determine the actual causes for the behavior they observe.
   ...
   While some links between time in child care and certain behaviors have been noted by researchers, it is impossible to conclude that extended child care causes children to behave aggressively or defiantly. Researchers also stress that the percentage of children demonstrating aggressive behavior in the study was well within the normal range for any population.
   Says Friedman, "We have no way in this study to attribute cause and effect. In the case of these findings, there is no way to attribute causality."
   ...
   And in a larger sense, the very nature of the study, plagued by such inevitable methodological problems as defining its subjective terms -- what is "aggression"? -- and the difficulty in assessing and factoring in intangible influences such as quality of family life and quality of child care, should caution researchers and the public alike against drawing sweeping conclusions.
   ...
   In her e-mail Weinraub added, "Certainly, it is premature for anyone, least of all developmental researchers, to interpret the meaning of this finding for public policy in light of the information so far and the complicated issues it raises."

MSNBC:

   [T]here is no inevitable link between non-maternal child care and aggression. In fact, studies of children raised in Israeli kibbutzes found these children quite the opposite of aggressive. They were more co-operative and peer-oriented than other children. And these kids spent more hours away from their mothers than most kids anywhere, often sleeping at night in "children's houses."

LA Times:

   [C]hildren who were in high-quality child-care centers were academically more advanced than their peers. Perhaps, researchers said, it is the more academically advanced children who are more aggressive; perhaps they are more bored or confident or rambunctious because they are used to school.

MSNBC:

   Researchers also suggest that stressed-out parents could be the causative factor.
   The latter would hardly be surprising. Unlike European societies, the U.S. has made little societal accommodation to the fact that nearly 70 percent of parents today are working.
   Schools still operate on the same hours as they did in the pre-industrial age. There is little government-subsidized day care, as there is in France and Sweden. Maternity and paternity leaves are short and usually unpaid, and vacation time is shrinking for American workers.
   ...
   If the aggression problem is real, and if it isn't caused by hours in day care, but by parental stress, working less could exacerbate it. That would be especially true if cutting down hours at work meant financial problems for parents, who would then experience more stress, and kids would be worse off.

Salon:

   [T]he observational, nonrandomized nature of the study means that scientists cannot rule out the possibility that the observed correlation is due to an unknown co-factor, such as the possibility that parents are more likely to place aggressive children in day care. Such cofactors are themselves, of course, speculative.

Salon letters to the editor:

   Why do the NICHD researchers think that day care is the /cause/ of the observed aggression? Isn't there a chance it's the other way around: that badly behaved kids are more likely to get put into day care, and more likely to be left there for more hours a day than well-behaved ones?
   ...
   It is, of course, possible that separation from Mom /does/ cause behavior problems. The way to test for that would be a study of identical twins where one twin was randomly assigned to go to day care while the other stayed home with Mom. If such a study turned up meaningful differences, then we could say we'd actually learned something. Until such a study is done, I don't know how NICHD can say that day care causes aggression. The opposite interpretation -- that aggressive kids are more likely to be sent to day care -- is just too plausible to ignore.

4) The "increased" aggressiveness is still entirely normal.

LA Times:

• Although 17% of kindergartners who had been in child care showed more assertive and aggressive behaviors, that proportion is the norm for the general population of children and adolescents. (Only 9% of children who spent most of their time with their mothers were rated by teachers as showing the more troubling behaviors.)
• In addition, researchers said that the statistics are very modest: Few children exhibited above-average behavior problems, and the problems were not drastic.

Boston Globe:

   [R]esearchers said that this bad behavior was at the upper end of normal, not in Charles Manson country.
   More to the point, as Deborah Vandell, a lead researcher from the University of Wisconsin points out, ''the proportion of aggressive behavior mirrors what we see in the population at large.'' It turns out that the same percentage of all school children - those who were and weren't in child care - also turn out to be ''highly aggressive.''
   This is not what I would call good news. But it offers a bit of perspective. Those in mommy-only care may be less aggressive, but we don't know why. Are these little kids socialized more carefully? Or have they not yet had a, um, fighting chance? As Vandell suggests, "You can't get into fights with peers if there are no peers."

Salon:

   Researchers also stress that the percentage of children demonstrating aggressive behavior in the study was well within the normal range for any population.
   ...
   Margaret Burchinal, a University of North Carolina researcher who oversaw the statistical side of the study, said in a statement last week that the aggressive behaviors displayed by children in the study "were typical of what you'd expect for a normal 4-year-old. We're not seeing that child care produces super-aggressive kids."

MSNBC:

   Exactly what was the behavior that caregivers and teachers observed? Was the aggression verbal or physical?
   And what about talking back and disobeying? It could be that smart, verbal kids talk back more and are harder to manage than other kids. There's a big difference between being a bully and being a kid who knows how to test the limits of tired, underpaid teachers -- or who is able to use verbal skills to get what he or she wants from other children.
   ...
   The aggression was in the "normal" range, not requiring professional attention.

5) The research found some areas where day care kids were better off.

• Center care in infancy is not associated with either positive or negative developmental outcomes.
• Children in higher quality child care arrangements during their first four and a half years of life scored higher on tests of cognitive skills and language ability than did children in lower quality care
• Children who spent more time in child care centers as opposed to other types of care displayed better language skills and had better short-term memory by the age of four and a half than did other children the same age.

6) My feminist rant.

I have to post this bit of data, because it really annoys me.

Salon:

   And what about the conclusion that the father seems not to be an adequate replacement for the mother at home? There were so few children cared for by the fathers in the study -- fewer than 100 out of 750 -- says [researcher Robert] Pianta.

What really ticks me off about the coverage of this study is that the brunt of the focus is still on the mothers. Almost every time that childrearing makes the news, it's the mother who gets the blame. It's always the woman who should quit work to stay home with the kids.

Most children do have fathers, and I'm really sick of comments that ignore that fact and try to put all the responsibility and blame solely on the mothers. Read any of the articles about this day care report, and it's always talking about working WOMEN, not working PARENTS.

MSNBC:

   Raising children is a complex process, and there's no style of parenting that is without problems. When mothers were mostly at home, in the l950s, social critics coined the term "momism" and said that American children were selfish and spoiled because of their over-protective mothers. Some went so far as to say that indulgent mothers were the reason that American servicemen broke under torture in Korea.
   Today, it's working women who are said to be harming their children, by not spending their every waking moment "relating" to their kids. But throughout history, children usually had multiple caretakers, and 50 years of scientific evidence finds that the children of working mothers show few differences in emotional or intellectual development from the children of at-home mothers.

Notice there's no mention of fathers in those paragraphs?
I had hoped that by the year 2001, we'd have gone beyond blaming women.