This systematic review aims to synthesize the literature on the effects of cross-linguistic transfer on Spanish/English bilinguals' reading comprehension skills. The search yielded at least 90 studies in which participants were Spanish/English bilinguals aged birth to Grade 12. Researchers assessed participants' decoding and/or linguistic comprehension skills in one of the target languages (i.e., English and Spanish) and their reading comprehension skills in the other language (e.g., cross-linguistic transfer). Included is an analysis of the research methodologies implemented in the identified studies and the assessments used to measure bilinguals' language and literacy development. Preliminary meta-analytic findings comparing studies that implemented methods that allow for causal inferences to those that provided only correlations will be included.