This study collected age-of-acquisition (AoA) norms for 19,716 simplified Chinese words provided by 1765 native speakers of Mandarin Chinese. Analysis of demographic factors revealed both gender and cohort differences in ratings and thus differences in trajectory of vocabulary development, suggesting the utility of AoA ratings to investigate individual differences and societal changes in levels of academic achievement. Moreover, consistent with past analysis conducted with English words, AoA ratings accounted for an extra portion of variance in lexical processing above and beyond the most prominent predictor, word frequency. Further analysis suggested that AoA ratings might be more predictive of processing low frequency words relative to high frequency words. Cross-language comparison also indicated that future research should explore the unique factors implicated in the processing of Chinese words.