PARENTS CAN BE very picky when shopping for their children's clothes. But without even realizing it, they may be far less discriminating when shopping for something that could cost a child's life. I'm talking about day care.

A recent trial should be a cautionary tale for all parents of young children. In February, a jury in Cambridge, Mass., convicted Ann Power of shaking to death 3-month-old MacKenzie Corrigan. She was one of 14 children at the day care that Power ran in her Reading home — more than double the number of children allowed by state law.

If the Corrigans are like other parents I've interviewed under similar circumstances, not only are they devastated but they also blame themselves. They wonder how they could have let this happen — even as they understand on a rational level that the only person to blame is the woman the jury convicted.

Yet parents rarely act as if they appreciate the stakes when they shop for day care. "People have a desire to be trusting," says Julia Wrigley, a sociologist at the City University of New York, who recently published the first large study of safety in day care. Too often, the parents focus on small reassurances, such as the cleanliness of the home, rather than signs that should be warnings. And too often they think that their job of evaluation ends when they make their selection.

Deaths in day care are not common, Wrigley notes, but her research found that they are 16 times more likely when the site is a private home, rather than a child-care center. And there were tip-offs that parents considering Power's day care would have been well advised not to choose it.

The Massachusetts Office of Child Care Services has a Web site, at which parents can view all licensed facilities; Power isn't on this list — and hasn't been since 1995, says spokeswoman Constantia Papanikolaou. (In Rhode Island, parents can get this kind of information by calling OPTIONS for Working Parents, at 401/272-7510.)

Had the Corrigans called the Office of Child Care Services to ask why Power's day care was not on its list, they would have learned that her license had been revoked, for overcrowding. In Massachusetts, a day care in a home may not have more than six children. (In Rhode Island, some facilities may have as many as eight. Parents can call 401/528-3623 to learn if anyone has complained about a day care here.)

When regulators close a Massachusetts facility, they call the parents and ask them to collect their children, says Papanikolaou. And they inform the parents of why they're closing it.

Yet Power simply reopened her day care. She was told to shut her doors twice more — in 1996 and 1999 — before MacKenzie Corrigan died. Through investigators' probes of her business, they learned that Power had urged the parents to say that they were her relatives, which would have exempted her from the licensing requirement.

There was one other red flag regarding Power's day care: the previous death of a baby there, in 1984. It was attributed to sudden infant death syndrome (SIDS), which kills apparently healthy babies without warning. The syndrome is a mystery, but we know that autopsies can't necessarily distinguish SIDS from suffocation; careful further investigation is required. We also know that some deaths attributed to SIDS years ago did not meet that standard; later analysis uncovered that the real cause of death was murder.

Why did parents continue to use an illegal day care that was run by someone who crammed in too many children, lied about it, and encouraged the parents to do the same? Some parents can't conceive of anyone's harming their child. Others are convinced that the caregiver is their friend, and that this will protect their child. Still others believe that the government wouldn't allow the operation of an unsafe facility.

Parents need to understand that they are the first line of protection for their children — and sometimes the only line. There simply aren't enough government investigators to go around, and facilities rarely stay closed even when, like Power's day care, they're cited for violations.

The bottom line is that parents should start thinking like investigators. They need to keep their eyes open, and talk to the other parents — and ask their children questions. If their kids are too young to question, they should drop in unannounced and check.

When parents have misgivings about a day-care operation, it's time to find someplace else. Even if that seems rude. Even if it's inconvenient. Because, as the Corrigans can attest, the stakes don't get any higher.

David Hechler is a journalist and a senior reporter at Corporate Counsel and The American Lawyer magazines. He is completing a book on day-care risks and challenges that parents face in finding safe places for their children. He is also a member of the PROTECT National Advisory Board.