This study investigated the association between reading disability (RD) and
internalizing and externalizing psychopathology in a large community sampl
e of twins with (N = 209) and without RD (N = 192). The primary goals were
to clarify the relation between RD and comorbid psychopathology, to test fo
r gender differences in the behavioral correlates of RD, and to test if com
mon familial influences contributed to the association between RD and other
disorders. Results indicated that individuals with RD exhibited significan
tly higher rates of all internalizing and externalizing disorders than indi
viduals without RD. However, logistic regression analyses indicated that RD
was not significantly associated with symptoms of aggression, delinquency,
oppositional defiant disorder, or conduct disorder after controlling for t
he significant relation between RD and ADHD. In contrast, relations between
RD and symptoms of anxiety and depression remained significant even after
controlling for comorbid ADHD, suggesting that internalizing difficulties m
ay be specifically associated with RD. Analyses of gender differences indic
ated that the significant relation between RD and internalizing symptoms wa
s largely restricted to girls, whereas the association between RD and exter
nalizing psychopathology was stronger for buys. Finally, preliminary etiolo
gical analyses suggested that common familial factors predispose both proba
nds with RD and their non-RD siblings to exhibit externalizing behaviors, w
hereas elevations of internalizing symptomatology are restricted to individ
uals with RD.