The study also emphasizes the need to look at many different factors that are important to the child's development, not just a narrow range of behavior. For example, abused children may perform relatively well on certain psychological tests but terribly on others. As a result, measuring only one dimension can lead to the false conclusion that abused children do not fare too badly.

The study began in 1975 when Dr. Byron Egeland, a psychologist at the University of Minnesota, received a grant from the National Center on Child Abuse and Neglect to examine families ''at risk for poor quality care'' of their children. The initial goal was to identify both the factors related to poor parental care and the factors that enable some mothers to care properly for their children despite disadvantaged circumstances.

The researchers tried to stack the deck in favor of a high percentage of mothers who would have difficulty fulfilling a parental role. All were poor, most with limited education, who were having their first child.

''We didn't want mothers to be influenced by their previous experiences with parenting and children,'' Dr. Egeland explained. Most of the women were young (40 percent were teen-agers) and unmarried (62 percent) and the overwhelming majority of the pregnancies (86 percent) were unplanned. Many lived under what the researchers called ''chaotic conditions,'' sometimes complicated by illegal drug use, alcohol abuse, prostitution, family rejection or wife- beating. The women's racial backgrounds were typical of the urban poor of the Minneapolis area: 80 percent white, 13 percent black and 7 percent Hispanic or American Indian.

The researchers initially chose 267 women to participate in the study, but about 60 of them have since dropped out. The women were selected in the last three months of their pregnancy. They and their resulting offspring were periodically evaluated by a variety of tests and observational techniques. Through the years, the ways the mothers interacted with their children were recorded and various measurements were made of the children's psychological, intellectual, motor and social development.

By the time the children were 12 to 18 months old, Dr. Egeland and his co-workers were struck by how many of the children had failed to develop a ''secure attachment'' to their mothers. A securely attached child is able to explore new environments in his mother's presence and is readily comforted by his mother in a new situation. Depending upon whether the mother lived with or apart from a husband or male companion or had no relationship with a man, 38 to 55 percent of the infants had not become securely attached to their mothers by the time they were 1 year old.

The findings prompted Dr. Egeland to ask Dr. L. Alan Sroufe, a child psychologist at the university who is an expert in mother-infant attachment, to join him as a co-investigator in what hoped to be a continuing project. The researchers were subsequently financed by the Maternal and Child Health Services of the Federal Department of Health and Human Services and are now supported by the Department of Education to follow the children until the age of 10.