Parents information about behavior, problems and life situation of children before and after first year of school were analysed and compared with data from teacher reports. At the end of first grade 131 parents were asked about behavior problems of their children using the child behavior checklist (CBCL) and additional items about living condition of the familiy and child. Findings were compared with those of a large epidemiological study conducted one year before in the same area using the same instruments. Additional teacher-reported data about behavior problems and school achievement were included. Comparing data before and after first year of school, no significant change in average CBCL total score could be observed. From parents view oppositional behavior was the most prevalent problem. There was a decrease of social problems. Children became more independent having more contact with peers. More children have their own television and computer at the end of first grade. Prevalence of headache and perfectionism as well as symptoms of tension and irritation increased. The most important problems from teachers' view are lack of attention and concentration affecting 32% of the first graders. Compared to the parents, teachers report only few oppositional and aggressive behavior. Achievement at school and behavior problems are highly correlated. Especially attention problems go along with low achievement at school. Parents' and teachers' ratings show an average correlation of r = .28 with the highest accord for attention problems and school achievement. The results of the study contribute to the question how children deal and cope with the new situation coming to school. The findings of a high rate of attention problems at school and the close relationship between behavior problems and achievement lead to the conclusion that an early prevention of behavior problems is essential to promote school performance.