This longitudinal quasi-experimental study examines the effects of Word Generation, a middle-school vocabulary intervention, on the learning, maintenance, and consolidation of academic vocabulary for students from English-speaking homes, proficient English speakers from language-minority homes, and limited English-proficiency students. Using individual growth modeling, we found that students receiving Word Generation improved more on target word knowledge during the instructional period than students in comparison schools did, on average. We found an interaction between instruction and home-language status such that English-proficient students from language-minority homes improved more than English-proficient students from English-speaking homes. Limited English-proficiency students, however, did not realize gains equivalent to those of more proficient students from language-minority homes during the instructional period. We administered follow-up assessments in the fall after the instructional period ended and in the spring of the following year to determine how well students maintained and consolidated target academic words. Students in the intervention group maintained their relative improvements at both follow-up assessments.