Noting that the kindergarten year is important in establishing competencies critical to children's success and achievement in school, and the lack of information on how children make the transition to kindergarten, this study examined differences in parental reports of children's adjustment behaviors for a large, nationally representative sample of beginning public school kindergartners. The focus of the research was on the prevalence of parent-reported adjustment problems of first-time public school kindergartners and whether some groups of children experience these adjustment problems more than others. The adjustment behaviors examined were: complaining about going to school, being upset or reluctant to go to school, and pretending to be sick to stay home from school. Data were from a subset of 13,602 children from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (ECLS-K). Parents reported that 72 percent of first-time public school kindergartners did not show signs of adjustment difficulty during the first 2 months of the school year. Thirteen percent showed one adjustment difficulty, and 15 percent exhibited two or more. Certain child, family, and kindergarten program characteristics were related to the percent of children who showed adjustment difficulties. Being male, having a disability, or living in a lower socioeconomic status family were associated with adjustment difficulties. Children attending full-day kindergarten programs and those in class sizes of 25 or more children were more likely to demonstrate adjustment difficulties even after controlling for other child and family characteristic differences. (Contains 6 data tables.) (KB)