Attention-deficit/hyperactivity disorder (ADHD) can be identified in the preschool years, but little is known about the correlates of ADHD symptoms in preschool children. Research to date suggests that factors such as temperament, personality, and neuropsychological functioning may be important in understanding the development of early ADHD symptomatology. The current study sought to extend this research by examining how cognitive and reactive control processes predict ADHD symptoms. Data were drawn from a larger study that measured the cognitive, social, and emotional functioning of preschool children. Eighty-seven children (aged 4-6 years) were evaluated using teacher report and laboratory task measures relevant to cognitive control (i.e., conscientiousness, working memory) and reactive control (i.e., neuroticism, delay of gratification) processes. In multiple regression analyses, cognitive control variables added unique variance in the prediction of both inattention and hyperactivity, but only reactive control variables added unique variance in the prediction of hyperactivity. The current findings align with past research suggesting that cognitive control processes (e.g., conscientiousness) are related to both inattention and hyperactivity/impulsivity, while reactive control processes (e.g., neuroticism) are more strongly related to hyperactivity/impulsivity in preschool children. Future longitudinal research utilizing various methods and measures is needed to understand how cognitive and reactive control processes contribute to ADHD symptom development.