The present study compared the performance of depressed youths and healthy controls on a modified mental counting task. The mental counting task was designed to capture processes associated with shifting the internal focus of attention by requiring participants to count random runs of words appearing on a computer screen. The words belonged to two different categories, and participants were required to maintain a count of the number of words in each category. Participants' reaction time to successfully update their counts and call for subsequent stimuli was measured. In particular, two versions of the modified counting task were developed: one incorporating neutral words and the other affective words. Overall, our findings in reaction time analysis suggest that depressed patients exhibited greater difficulty switching their internal focus of attention in the affective task when compared to healthy controls, even when controlling for their rate of accuracy. However, there was no significant difference between the groups during the neutral task. Results support the hypothesis that depression is related to impaired internal attention shifting when processing affective material.