A study examined how the family structure has changed over time in contemporary realistic children's literature for middle readers. There is an ongoing debate in this country about what defines a family and whether it is in transformation or becoming extinct. Since 1960 there is evidence that the family structure has changed. The books selected in the study were limited to 35 books published in the United States from 1955 to 1970 and 35 books published in the United States from 1980 to 1995. Results of the analyses of the stories indicated that there was a decrease in the depiction of the traditional two-parent family and an increase in the single parent family. The majority of the stories still represent parents with biological children. The number of children represented has decreased, and parents had fewer children in the later time period. The cause of a non-two-parent family in the earlier time period was because the parents had died and in the later time period it was because parents had divorced. In all cases, the father worked outside the home; however, the cases where the mother worked outside the home increased. Regarding family structure problems, the majority of child protagonists did not have conflicts. There was an increase in problems concerning family structure, but the percentage of problem resolution also increased. (Contains 6 tables of data and 25 references; a coding sheet is appended.) (Author/CR)