Despite acknowledgement of the limited English vocabularies demonstrated by many language minority (LM) learners, few studies have identified skills that relate to variation in vocabulary growth in this population. This study investigated the concurrent development of morphological awareness (i.e., students' understanding of complex words as combinations of meaningful smaller units) and vocabulary for LM learners in early adolescence. A cohort of Spanish-speaking LM learners (n = 90) was followed from fourth through seventh grade and assessed annually. Latent growth modeling results indicated a strong relationship between rates of growth in the two skills, such that learners with rapid growth in derivational morphological awareness also demonstrated rapid growth in vocabulary. Despite positive vocabulary growth during this period, the learners remained far below national norms. Findings highlight the need for language-focused instructional intervention for this population and suggest that morphological awareness may be a promising point of leverage for such instruction.