The latest results of a long-running child-care study of toddlers to teens underscore what makes a lasting difference for kids: quality of parenting and quality of care. What's helpful to know when you're selecting child care:

At age 15, children who spent long hours in day care as preschoolers are slightly more impulsive and more prone to take risks than teenagers whose younger years were spent largely at home, the new study suggests.

When these same children were observed at age 4 1/2 and younger, the results were similar: Children in nonmaternal care more than about 30 hours a week had slightly more behavioral problems in kindergarten.

The early findings about aggression in day care grabbed media attention and elevated the working-mommy guilt factor. The differences in behavior are slight but important, say the study's researchers. But three other findings deserved attention as well, the researchers said, and remain applicable nearly a decade later.

--Good parenting matters: Children whose mothers are responsive and sensitive were less likely to be rated as aggressive by their parents and teachers.

--Quality of care matters: Children whose caregivers are sensitive and use stimulating material in a structured environment tend to have stronger academic skills.

--Type of care matters: When caregivers have more formal training and smaller class sizes, children tend to have stronger academic skills.

The National Institute of Child Health and Human Development enrolled 1,364 children in 1991 to examine how differences in child care experiences relate to children's social, emotional, intellectual and language development, and to their physical growth and health. The latest phase of the study, the teenagers, was published recently in the May/June issue of "Child Development."

Part of the day-care problem isn't news to parents: quality. Of the more than 1,364 kids first enrolled in the child-care study in 1991, 60 percent were judged to have low- or moderately low-quality care, and 16 percent had care that the researchers rated as high quality.

The latest phase of the federally funded study reflects the group's past findings on the importance of good-quality child care: of attentive, trained and well-paid caregivers, a low turnover rate of staff, group size, clean and safe facilities, and stimulating activities. For teenagers who had such care, the study found slight advantages in academic performance.

Good news: One of the strongest predictors of a child's development is positive care-giving: sensitive, encouraging and frequent interactions between the caregiver and the child.

To assess quality, the researchers factored in these behaviors that parents can try to observe when deciding what is best for their child:

--Is the caregiver generally in good spirits and encouraging when interacting with the child? Does the caregiver smile often at the child?

--Does the caregiver hug the child, pat the child on the back or hold the child's hand? Does the caregiver comfort the child?

--Does the caregiver repeat the child's words, comment on what the child says or tries to say and answer the child's questions?

--Does the caregiver encourage the child to talk or communicate by asking questions that the child can answer easily, such as "yes" or "no" questions, or asking about a family member or toy?

--Does the caregiver talk in other ways, such as praising or encouraging; teaching by having the child repeat phrases or naming shapes; singing songs; and telling stories?

Parenting tip: Accreditation by programs such as the National Association for the Education of Young Children or the quality rating systems developed by states can be useful in helping parents identify good child-care programs.

Betsy Flagler, a journalist based in Davidson, N.C., is a mother and teaches preschool. Reach her at p2ptips@att.net.