Background: Models of attention-deficit/hyperactivity disorder (ADHD) suggest developmental influences may feed into components of the disorder separately from associated disruptive behavior problems. We investigated this in terms of key personality/temperament traits of Reactive and Effortful Control, Resiliency, and Emotionality. Methods: A sample of 179 children (age 6-12, 63% boys), of whom 92 had ADHD, 52 were Controls, and 35 were borderline or not otherwise specified cases of ADHD, were examined. Dispositional trait scores were derived from parent-completed California Q-sort and the Early Adolescent Temperament Questionnaire. Child ADHD symptoms were evaluated using maternal structured diagnostic interview and teacher-completed symptom ratings. Results: Traits were differentially associated with symptoms. Reactive Control was related to hyperactivity-impulsivity as rated by both parents and teachers. Negative Emotionality was related to oppositional-defiance. Resiliency was primarily related to inattention-disorganization as rated by both parents and teachers; Effortful Control was related uniquely to inattention in parent but not teacher data. A moderation effect emerged; the relationship between parent-rated Negative Emotionality and teacher-rated ADHD symptoms was stronger for children with high levels of both Reactive and Effortful Control. Conclusions: Results are interpreted in relation to a two-pathway model of ADHD; regulation problems contribute to the emergence of symptoms of inattention-disorganization, reactive or motivational control problems to the emergence of hyperactivity-impulsivity, and these are distinct from negative affectivity. Children with regulation deficits and a reactive motivational style are especially at risk for the development of ADHD.