Purpose Behavior and temperament (e.g., emotional reactivity, self-regulation) have been considered relevant to stuttering and its developmental course, but the direction of this relation is still unknown. Knowledge of behavior difficulties and temperament in childhood stuttering can improve screening and intervention. The current study examined both directions of the relationship between stuttering and behavior difficulties and temperament and between persistent stuttering and behavior difficulties and temperament across childhood. Method This study was embedded in the Generation R Study, a population-based cohort from fetal life onward in the Netherlands. We analyzed data from 145 children (4.2%) with a history of stuttering (118 recovered, 27 persistent) and 3,276 children without such a history. Behavior and temperament were repeatedly assessed using parental questionnaires (Child Behavior Checklist) and Infant/Child Behavior Questionnaire between 0.5 and 9 years of age. Multiple logistic and linear regression analyses were performed. Results Six-month-old children who were less able to "recover from distress," indicating poor self-regulation, were more likely to develop persistent stuttering later in childhood (odds ratio = 2.05, 95% confidence interval (CI) [1.03, 4.05], = .04). In the opposite direction, children with a history of stuttering showed more negative affectivity (β = 0.19, 95% CI [0.02, 0.37], = .03) at 6 years of age than children without such a history. Stuttering persistence was associated with increased internalizing behaviors (β = 0.38, 95% CI [0.03, 0.74], = .04) and higher emotional reactivity (β = 0.53, 95% CI [0.09, 0.89], = .02) at the age of 9 years. Conclusions Behavior and temperament were associated with stuttering persistency-seemingly as both predictor and consequence-but did not predict a history of stuttering. We suggest that children who persist in stuttering should be carefully monitored, and if behavioral or temperamental problems appear, treatment for these problems should be offered. Supplemental Material https://doi.org/10.23641/asha.16869479.