In this study, I used individual growth modeling methods to examine the English word-learning trajectories of adolescent students (N = 278) whose parents speak English at home (n = 210) and those whose parents speak a language other than English (n = 68). Sixth- (n = 130) and seventh-grade (n = 148) students attending an urban middle school took part in the study, with each student contributing up to four occasions of vocabulary-achievement data across three school years. I used the group reading and diagnostic evaluation (GRADE), a 40-item, group-administered assessment to measure vocabulary achievement. Students also provided information about the amount of time they spent reading independently during the summer and during the school year. Principal predictor variables included days between assessments, student home language, student free and reduced lunch status, time spent independent reading, and a dummy variable for the number of summers experienced between testing periods. On average, middle-school students experienced a loss of vocabulary over the summer, however students who spoke a language other than English at home had more pronounced summer setback and steeper learning trajectories, even when controlling for well-known predictors of vocabulary like independent reading and predictors of summer loss like free and reduced lunch status. These findings corroborate research showing low-income students experience summer loss, but suggest that in urban schools serving mostly low-income students, home-language status may be a stronger predictor of summer loss than socio-economic status or reading amount.