Focusing on text summary speaking tasks, the present study investigated the effects of the activation of phonological representations during text comprehension (operationalized by read-aloud assistance) on the subsequent retelling speech. A total of 24 Japanese learners of English completed text summary speaking tasks under two conditions: (a) reading without read-aloud assistance and (b) reading with read-aloud assistance. Their speech data were analyzed by lexical overlap indices (i.e. the ratio of characteristic single-words and multiword sequences) and by fluency measures capturing three major dimensions of fluency—speed, breakdown, and repair fluency. The results showed that read-aloud assistance directly facilitated lexical overlaps with source texts and indirectly improved speed and repair fluency. Furthermore, read-aloud assistance was found to affect the interrelationship between lexical overlaps and utterance fluency. The findings suggested that read-aloud assistance might help second language learners to store multiword sequences as a single unit (i.e. chunking) during text comprehension.