The present study investigated the efficiency with which younger and older adults allocate attention to relevant and irrelevant stimuli. The model of attention guiding this research links the orienting response with the allocation of attention and habituation with the inhibition of the allocation of attention. We adapted a paradigm developed by Iacono and Lykken (1983) in which subjects are instructed unambiguously either to attend to or to ignore a series of innocuous tones, and the skin conductance orienting response elicited by each tone is measured. Results revealed that young subjects instructed to ignore the tones habituated more quickly than did those instructed to attend to the tones. However, older adults exhibited nondifferential orienting across the 2 instruction conditions. These results suggest an age-related deficit in the ability to inhibit attention to irrelevant stimuli.