A key question in cognitive neuroscience is how brain activity orchestrates brain function. Recent advances assign an important role to oscillatory brain activity. This type of activity is thought to reflect the assembly of neuronal elements into functional networks as an essential component of information processing. My talk will cover our attempts to unravel the role of brain oscillations in attentional selection and perception using electroencephalography/EEG (to reveal correlative brain-behavior relationships) as well as interventional techniques such as non-invasive brain stimulation and visual flicker (to reveal causal relationships). Covering spontaneous and attention-related EEG fluctuations at baseline, and post-stimulus EEG signals, this has helped to identify some of the electrophysiological correlates/substrates of perception over the posterior brain, including attention-modulated alpha activity. Experimental manipulation of task demands and stimulus content has revealed neuronal signals of spatial and feature selection. The use of interventional approaches has suggested that these signals are causally involved in implementing function. Implications and future directions for clinical applications are discussed.