Language learner attitudes have been linked to motivation, willingness to communicate, and attainment in second language (L2) learning research. Yet, explorations of learner attitudes remain scarce, especially concerning learners’ perspectives on the language instruction they receive in schools. To contribute to a more complete picture of L2 English instruction, we gathered data from 2,721 adolescent learners of English in German, Norwegian, and Polish schools through the English Language Teaching (ELT) Survey. Our measures of attitudes included summarized ratings of classes, semantic differentials, and responses to a reflective scale, all of which we subjected to inferential analyses. To explore the reasons behind learners’ attitudes towards L2 English instruction, we supplemented quantitative data with qualitative insights and interpreted attitudinal differences in the three countries. Although the evaluations of English lessons appeared relatively positive, participants’ perceptions of their L2 English instruction were largely unfavourable. English lessons were most often labelled monotonous by students learning in German and Polish schools. This remains in stark contrast to earlier findings on learners’ attitudes to English as a school subject from various countries. At the same time, our analyses revealed statistically significant differences across the three countries, with students in Norwegian schools being the most enthusiastic about their L2 English classes, and students in Polish schools being the most critical. These differences were largely parallel to the variation in participants’ self-assessment of attainment in English and, to some extent, their most recent marks in English. In the process of a reflexive thematic analysis, we identified five main themes illustrating explicit criticism related to a narrow scope of teaching methodologies, limited opportunities for communication, lack of real-life relevance, teacher-related challenges, and little emotional-motivational support. These qualitative insights allowed us to explain reasons behind learners’ generally negative attitudes. Our findings highlight the need to consider learners’ voices in research on attitudes to L2 instruction.