Physiological studies in humans and monkeys have revealed that, in response to an instruction to attend, areas of sensory cortex that code the attributes of the expected stimulus exhibit increases in neural activity prior to the arrival of the stimulus. Models of selective visual attention posit that these increases in activity give attended stimuli a processing advantage over distracting stimuli. Here, we test two key predictions of this view by using functional magnetic resonance imaging to record human brain activity during a cued voluntary orienting task. First, we tested whether pre-stimulus modulations are observed during both cued spatial and cued feature attention. Secondly, we tested whether the magnitude of pre-stimulus modulations predicts behavioral performance. Our results indicate that cue-triggered expectation of targets with particular spatial or nonspatial features activates areas of the visual cortex selective for these features. Furthermore, the magnitude of the cue-triggered modulations correlated with behavioral measures, such that those subjects who exhibited relatively large pre-stimulus modulations of activity performed better on the behavioral task. These findings support the view that top-down control systems bias activity in sensory cortices to favor the processing of expected target features and that this bias is related to behavior.