A foundation of second language motivational theory has been that motivation contributes to explaining variance in language learning proficiency; however, empirical findings have been mixed. This article presents an innovative approach to exploring L2 proficiency and motivations of teenage English language learners in Madrid, Spain (N = 1773). Participants completed a multiskill English language test, plus an eight-scale questionnaire operationalizing constructs from Dörnyei's L2 Motivational Self System (Dörnyei, 2005). Data were analysed using Latent Variable Mixture Modeling, a person-centered profiling approach. Results indicated five distinct classes of students, characterized by differing motivation-proficiency profiles. The importance of this study is that the analysis does not assume a homogenous relationship between motivational traits and proficiency levels across the learner sample; whilst there is undoubtedly a connection between the two areas, it is not a straightforward correlation, explaining to some extent discrepancies in previous findings and laying groundwork for further, more nuanced, investigation.