<p>This study investigates the dynamic mechanisms underpinning word reading and writing development among Chinese mid-elementary school children. We followed 161 Chinese students from grade 3 to grade 4 (60% boys; M_<i>age</i> = 9.33–10.33&#xa0;years) and assessed them on metalinguistic awareness, word reading, and writing (dictation). Findings revealed a bidirectional relation between word reading and writing during children’s transition from grade 3 to halfway grade 4. However, this reciprocal relation vanished as children furthered till the end of grade 4. Moderated cross-lagged panel analyses indicated that phonological and morphological awareness significantly moderated the influence of word reading on subsequent writing, but not vice versa. Specifically, the impact of word reading on later writing was robust among children with low phonological and morphological awareness, but weak among those with high phonological and morphological awareness. Results illuminate the dynamic interplay between word reading and writing, which is proportional to levels of metalinguistic awareness, and underscore the importance of oral metalinguistic experiences (phonological and morphological awareness) towards a balanced development of word reading and writing.</p>