This study attempts to identify potential school problems in preschool children in order to facilitate the provision of relevant information for systematic screening and early guidance. Data from the first 14 months (to the end of the preschool period) of a longitudinal study extending from 4 1/2 years of age to the end of second grade are reported. The children were tested twice. At the mean age of 58 months various individual tests for cognitive, linguistic and perceptual development were administered. Classroom behavior was rated by the teacher and neuromotoric functioning was examined by the school doctor. One year later at a mean age of 72 months, the tests and classroom observations were repeated. Results showed almost no sex differences in IQ, linguistic competence, or other aspects of cognitive functioning. Boys and girls were equally represented in the at risk group. Age differences were far more pronounced in the first part of the study than in the second. Socioeconomic status had an increasing influence on test results over the 14 months. Changes in cognitive development were significantly related to socioeconomic status and school. The age of the child and behavior ratings of the teacher made no independent contribution to the predictability of change. Socioeconomic status was strongly related to whether young preschoolers at risk for school problems showed improvement in the preschool period or not. (Author/JMB)