We examined three questions. First, do reading difficulties increase children's risk of behavioral difficulties? Second, do behavioral difficulties increase children's risk of reading difficulties? Third, do mathematics difficulties increase children's risk of reading or behavioral difficulties? We investigated these questions using (a) a sample of 9,324 children followed from third to fifth grade as they participated in a nationally representative dataset, (b) multilevel logistic regression modeling, and (c) statistical control for many potential confounds. Results indicated that poor readers in third grade were significantly more likely to display poor task management, poor self-control, poor interpersonal skills, internalizing behavior problems, and externalizing behavior problems in fifth grade (odds ratio [OR] range = 1.30-1.57). Statistically controlling for a prior history of reading difficulties, children with poor mathematics skills in third grade were also significantly more likely to display poor task management, poor interpersonal skills, internalizing behavior problems, and reading difficulties in fifth grade (OR range = 1.38-5.14). In contrast, only those children exhibiting poor task management, but not other types of problem behaviors, in third grade were more likely to be poor readers in fifth grade (OR = 1.49). Poor readers in third grade were extremely likely to still be poor readers in fifth grade (OR = 19.69).