ERP measures may index genetic risk for psychopathology before disorder onset in adolescence, but little is known about their developmental rank‐order stability during this period of significant brain maturation. We studied ERP stability in 48 pairs of identical twins (age 14–16 years) tested 1 year apart. Trial‐averaged voltage waveforms were extracted from electroencephalographic recordings from oddball/novelty, go/no‐go, and flanker tasks, and 16 amplitude measures were examined. Members of twin pairs were highly similar, whether based on ERP amplitude measures (intraclass correlation [ICC] median = .64, range = .44–.86) or three factor scores (all ICCs ≥ .69) derived from them. Stability was high overall, with 69% of the 16 individual measures generating stability coefficients exceeding .70 and all factor scores showing stability above .75. Measures from 10 difference waveforms calculated from paired conditions within tasks were also examined, and were associated with lower twin similarity (ICC median = .52, .38–.64) and developmental stability (only 30% exceeding .70). In a supplemental analysis, we found significant developmental stability for error‐related negativity (range = .45–.55) and positivity (.56–.70) measures when average waveforms were based on one or more trials, and that these values were equivalent to those derived from averages using the current field recommendation, which requires six or more trials. Overall, we conclude that the studied brain measures are largely stable over 1 year of mid‐ to late adolescence, likely reflecting familial etiologic influences on brain functions pertaining to cognitive control and salience recognition.