This study explores the effects of various motivational variables operating within 44 English classes on 1-year-long gains in the English reading proficiency of 1,149 Japanese university students. The study adds new knowledge to the recent outcomes of second language (L2) motivational studies in 3 major ways. First, the explanatory variables include the participants' own motivation as well as the class norms ("ethos") shared by class members, some of which (e.g., career aspirations) were not directly related to their L2 learning. Second, multi-level modeling enabled a simultaneous analysis of L2 proficiency growth over 1 year at both the individual and the class levels. Third, its explanatory sequential mixed methods design (Cresswell, 2014) demonstrated how the participants' own accounts help to explain the initial quantitative results in ways the researchers' outsider speculations could not. The statistical results indicate that the 44 classes grew in L2 reading abilities at significantly different rates over the year and that these differences can be explained by the students' perceptions of their classmates' normative career aspirations (among other predictors). These results suggest that being surrounded by classmates with high career aspirations may lead to higher motivation to study the L2 even if students are not highly motivated in the beginning.