Research has shown that regular rhythmic primes improve gram-maticality judgments of subsequently presented sentences compared with irregular rhythmic primes. In the theoretical framework of dynamic attending, regular rhythmic primes are suggested to act as driving rhythms to entrain neural oscillations. These entrained oscillations then sustain once the prime has finished , engendering a state of global enhanced activation that facilitates the processing of subsequent sentences. Up to now, this global rhythmic priming effect has largely been shown with primes that are approximately 30 s or more. To investigate whether shorter primes also facilitate grammaticality judgments, two experiments were run on two groups of children aged 7 to 9 years (Ms = 8.67 and 8.58 years, respectively). Prime durations were 8 and 16 s in Experiment 1, and they were 16 and 32 s in Experiment 2. Rhythmic priming was observed in Experiment 2 for 32-s primes, as observed previously. Furthermore, positive correlations were found between reading age and performance level after regular primes for both 8-s and 16-s primes in Experiment 1 and for 32-s primes in Experiment 2. In addition, the benefit of the regular primes increased with chronological age for the 32-s primes in Experiment 2. The findings suggest that (at least) 32-s primes are optimal in global rhythmic priming studies when testing children in the current age range and that results may be modulated by chronological age and reading age. Results are discussed