In this meta-analysis, we examined whether children identified with reading difficulties (RD) evidence writing difficulties. We included studies comparing children with RD with (a) typically developing peers matched on age (k = 87 studies) and (b) typically developing younger peers with similar reading capabilities (k = 24 studies). Children identified with RD scored lower on measures of writing than their same age peers (g = -1.25) when all writing scores in a study were included in the analysis. This same pattern occurred for specific measures of writing: quality (g = -0.95), output (g = -0.66), organization (g = -0.72), sentence skills (g = -0.78), vocabulary (g = -1.17), syntax (g = -1.07), handwriting (g = -0.64), and spelling (g = -1.42). Differences in the writing scores of children identified with RD and same age peers were moderated by whether the writing assessment was a norm-referenced or researcher-designed measure when all writing measures or just spelling were included in the analyses. Depth of orthography for studies involving European languages also moderated differences in the spelling scores of children identified with RD and same age peers. Finally, children identified with RD scored lower on writing than younger peers with similar reading capabilities (g = -0.94) and more specifically on spelling (-0.93). We concluded that children with RD experience difficulties with writing, providing support for theoretical propositions of reading and writing connections as well as the importance of writing instruction for these students.