Cross-language effects of Spanish derivational awareness on English vocabulary and reading comprehension were studied in Spanish-speaking English Language Learners (N = 90) in grades four and seven. The role of cognate vocabulary in cross-language transfer of derivational awareness was also examined. Multivariate path analyses controlling for age, length of time in Canada, nonverbal reasoning, English phonological awareness, and English word reading revealed that Spanish derivational awareness was related to English cognate vocabulary, but not to English noncognate vocabulary. In addition, there was an indirect contribution of Spanish derivational awareness to English reading comprehension via English cognate vocabulary and English morphological awareness. Findings suggest that knowledge of cognates facilitates the transfer of Spanish derivational awareness to English vocabulary and reading comprehension. These findings have theoretical, pedagogical, and clinical implications.