The research objective was to examine the stability of difficulties in the comprehensive school. Behavior problems, speech disorders and difficulties in reading and writing were defined as difficulties in school. The identification of the difficulties was based on teacher's assessments and diagnostic tests. The subjects were children who started comprehensive school in 1979 in Jyvaskyla, Finland. Information about some of the pupils was obtained in preschool. By means of a follow-up study information about 385 pupils was gained from the beginning untill the end of the comprehensive school. The stability of behavior problems depends on the factors that have had an effect on the emergence of those problems. The classification of the underlying factors is based on Reinert's genetic, physiological, neurological, psychological and sociological explanatory models. The relations between behavior problems and difficulties in reading and writing, and one's primary position to the other have been presented by means of Ericson's models. The research results indicated that certain disturbances are more stable than others and remain unchanged year after year. Disturbances that were found to be the most constant were negative attitude towards teacher and school, disturbing talkativeness, and personality disorders among boys. About half of the pupils who suffered from these disturbances in the first grade still had them in the ninth grade. Difficulties in reading and writing also showed great stability year after year: over 60 % of the upper level pupils who were receiving remedial reading and writing assistance were given it during the first two years at school. The predictability of problems differed among boys and girls. Discipline problems and difficulties in reading and writing among the first grade boys predicted discipline problems among the ninth-graders. Predictive symptoms among girls were merely linguistic ones: speech disorders and difficulties in reading and writing. Any indication of personality disorders emerging among girls at the school leaving age could not be found at the beginning of school, but among boys such indications were detected during the first two years at school. As a result of the comparison of which disturbance reaches the primary position to the other the researcher came into the conclusion that difficulties in reading and writing lead to discipline problems. In the same way, speech defect at the beginning of school predicted forthcoming behavior problems. The research results reinforced the idea that the teacher is able to assess and predict pupil's school achievement at the end of the comprehensive school.