How do event related potentials (ERPs) reflecting auditory processing develop across adolescence? Such development was described for five ERP components in four groups of 11 healthy participants with mean ages of 10, 14, 17, and 21 years. Data from 19 sites during diffuse (passive) and focused (discrimination) attention in a three-tone oddball were analyzed to see how ERP loci varied with age for tone type attention condition, and for four types of difference waves reflecting nontarget and target comparison. Age interacted with site for most components. P1 loci sensitive to rare tones moved postoriorly and N1 loci lost their right bias in early puberty. The P2 loci did not move anterior to Council adulthood N2 amplitude, sensative to attention condition, developed a frontal focus by 17 years. Right biased P3 loci moved lo the midline with focused attention similarly in all age groups. Difference waves developed in three stages; In 10-years-old participants early deflection (<150 ms) were diffusely distributed; in mid adolescent participants, the main frontal negative component (150-300 ms) became well formed and lost an earlier right bias: and for participants 17 years old and older, the late positive complex developed a right bias in target-derived waves. Latency decreases for early frontal components were marked in participants 10–14 years old and for later posterior components m participants 14–17 years old. Major developments appeared at the onset of adolescence in early stimulus selection processes and during adolescence in the in the differential use of this information (N2- and P3-like latencies).