This study examined the developments in children’s externalizing problems and interest in reading during their first four years of school (Grades 1-4) and investigated whether this development predicted the children’s Grade 6 reading skills and educational aspirations. Data comprised (1) teachers’ ratings of externalizing problems and children’s (N = 642; 43% girls) self-ratings of their interest in reading, collected between Grades 1 and 4, and (2) measures of reading fluency and comprehension, and children’s self-reports of educational aspirations, collected at Grade 6. First, latent growth modeling showed that a higher level of externalizing problems in Grade 1 was associated with a lower concurrent interest in reading. Second, a positive association between the initial level of interest in reading and a linear change in externalizing problems indicated that children with a lower interest in reading in Grade 1 were rated by teachers as exhibiting higher levels of externalizing problems, which nonetheless declined over the course of their first four years of school more than among other children. Third, a higher initial level of externalizing problems with a linear change in these problems across Grades 1-4 was a predictor of lower subsequent educational aspirations and poorer reading comprehension in Grade 6. Analysis of the indirect effects indicated that a higher level of externalizing problems was associated with a lower concurrent interest in reading, which, in turn, was related to poorer future reading fluency and lower educational aspirations. The findings imply that problem behaviors are interlinked with academic skill development and motivation across the first six years of school.