The downward extension of psychopathic traits to childhood and adolescence proved to be important in both research and clinical practice. The current study investigates how distinct psychopathic traits (i.e., callous-unemotional traits, narcissism, impulsivity) contribute to the prediction of conduct disorder (CD) symptoms, and whether these associations vary as a function of age. Further, we aimed to examine the variability in mean levels of psychopathic traits from age 9 to age 20 in a large community sample (N = 9136) using cross-sectional analysis. The study’s findings provided evidence for age variability in psychopathic traits, since narcissism was found to be more prevalent from age 13–15, impulsivity from age 13 to 20, and CU traits from age 15–18. These findings demonstrate that psychopathic traits are less prevalent during childhood than adolescence. Further, the pattern of association between CD symptoms and psychopathic traits also displayed variability by age. Specifically, even though the overall regression of psychopathic traits on CD symptoms suggested that the three psychopathic dimensions had comparable impact on CD, the separate regressions by age group suggested that impulsivity was the strongest predictor of CD in childhood and early adolescence (ages 9–14), while narcissism was the strongest predictor of CD in mid-adolescence (ages 15–17). In contrast, callous-unemotional traits had a more stable effect on CD symptoms across time. Current evidence can inform existing attempts for the developmental extension of the construct of psychopathy to childhood and adolescence.