Lexical competition that occurs as speech unfolds is a hallmark of adult oral language comprehension crucial to rapid incremental speech processing. This study used pause detection to examine whether lexical competition operates similarly at 7-8 years and tested variables that influence "online" lexical activity in adults. Children (n = 20) and adults (n = 17) were slower to detect pauses in familiar words with later uniqueness points. Faster latencies were obtained for words with late uniqueness points in constraining compared with neutral sentences; no such effect was observed for early unique words. Following exposure to novel competitors ("biscal"), children (n = 18) and adults (n = 18) showed competition for existing words with early uniqueness points ("biscuit") after 24 hr. Thus, online lexical competition effects are remarkably similar across development.