The present study examined the development of elevated startle reactivity in anticipation of mild anxiogenic procedures in school-age children with current anxiety disorders and in those at-risk for their development due to parental anxiety. Startle blink reflexes and skin conductance responses were assessed in 7 to 12 year old anxious children (N=21), non-anxious children at-risk for anxiety by virtue of parental anxiety disorder status (N=16) and non-anxious control children of non-anxious parents (N=13). Responses were elicited by 28 auditory startle stimuli presented prior to undertaking mild anxiogenic laboratory procedures. Results showed that group differences in startle reactivity differed as a function of children's age. Relative to control children for whom age had no effect, startle reflex magnitude in anticipation of anxiogenic procedures increased across the 7 to 12 years age range in children at-risk for anxiety disorders, whereas elevations in startle reactivity were already manifest from a younger age in children with anxiety disorders. These findings may suggest an underlying vulnerability that becomes manifest with development in offspring of anxious parents as the risk for anxiety disorders increases.