The ability to maintain a conversation with one person while at a noisy cocktail party has often been used to illustrate a general characteristic of auditory selective attention, namely that perceivers' attention is usually directed to a particular set of sounds and not to others. Part of the cocktail party problem involves parsing co-occurring speech sounds and simultaneously integrating these various speech tokens into meaningful units ("auditory scene analysis"). Here, we review auditory perception and selective attention studies in an attempt to determine the role of perceptual organization in selective attention. Results from several behavioral and electrophysiological studies indicate that the ability to focus attention selectively on a particular sound source depends on a preliminary analysis that partitions the auditory input into distinct perceptual objects. Most findings can be accounted for by an object-based hypothesis in which auditory attention is allocated to perceptual objects derived from the auditory scene according to perceptual grouping principles.