The present developmental study aimed to trace changes in response expectation, preparation, conflict monitoring and subsequent response inhibition from 6 years of age to adulthood. In two groups of children (6-7 and 9-10 years old) and young adults (1923 years old), behavior and event-related brain activity (ERP) in a CPT-AX task was measured. Hits, false alarms, inattention and impulsivity scores and ERP measures of conflict monitoring and inhibition (Nogo-N2 and P3), cue-orientation and prestimulus target expectation (cue-P2 and P3) and response preparation (Contingent Negative Variation; CNV) were collected. Behavioral measures indicated that attention processes developed most strongly before age 10, whereas impulsive behavior only started to diminish after the age of 10. Nogo-N2 effects were largest and more widely distributed across fronto-parietal electrodes in 6-7-year olds and decreased linearly with age. Nogo-P3 effects showed an opposite pattern by being absent in the youngest children, starting to develop at age 9-10 and reaching maturity in young adulthood. These developmental behavioral and ERP results are supportive of links between Nogo-N2 and conflict monitoring and Nogo-P3 and response inhibition and suggest that both are liable to different developmental progress. Furthermore, enhanced cue-P3 activity in both 6-7 and 9-10-year olds was argued to reflect a higher level of Go-stimulus expectation, that might cause them to experience more conflict on subsequent Nogo-trials, when the 'not- expected' stimulus appears. On the other hand, young children's reduced preparatory CNV activity was interpreted as a sign of reduced response priming caused by yet immature fronto-parietal networks involved in motor regulation.