Content knowledge and comprehension: A meta-analytic review of correlational and causal associations

We examined (a) the relation between content knowledge and comprehension (both reading and listening comprehension) using correlational data and (b) the impact of content knowledge instruction on content knowledge and comprehension using causal data. Moderation by assessment, person, instruction, and study quality characteristics was systematically examined. For causal data, listening comprehension was excluded from moderation analysis due to insufficient studies. Correlational data from 108 studies, 441 correlation coefficients, and N = 68,301 participants showed that content knowledge was moderately related to comprehension with an identical magnitude for listening comprehension and reading comprehension (r = .41). The relation with reading comprehension was stronger when content knowledge was assessed using norm-referenced tasks (r = .50) than when it was assessed using researcher-developed tasks (r = .39). Causal data from 55 studies, 304 treatment effect sizes, and N = 18,540 participants showed that content knowledge instruction improved content knowledge (g = 1.36) and reading comprehension (g = 0.44), but not listening comprehension (g = 0.13). Effects on reading comprehension differed: research-developed tasks (g = 0.51) compared to norm-referenced comprehension assessments (g = 0.21); knowledge activation (g = 0.66) compared to knowledge building (g = 0.19); and studies with an N of 1 design (g = 0.67) compared to those that did not (g = 0.18). The findings highlight the importance of content knowledge in comprehension while highlighting the need to consider variation in the relation and impact by assessment, instruction, and study quality features. Future directions are discussed. (PsycInfo Database Record (c) 2025 APA, all rights reserved).