Language anxiety (LA) is “the worry and negative emotional reaction when learning and using a second language and is especially relevant in a classroom where self-expression takes place” (Gregersen & MacIntyre, 2014, p. 14). In the present study, particular attention is drawn to the development of students’ communicative competence and speaking proficiency in English-as-a-foreign-language (EFL) classrooms. The prevalence and effects of foreign language speaking anxiety (FLSA) were examined among Swedish EFL lower secondary school students, reporting the triggers of foreign language anxiety (FLA) and FLSA from the perspective of pupils and teachers. A mixed-methods approach was applied to collect data from pupils (N=273) where a self-report questionnaire, a modified version of the Foreign Language Classroom Anxiety Scale (FLCAS) operationalised originally by Horwitz, Horwitz, and Cope (1986) is administered, plus open-ended semi-structured interviews with open-ended and closed questions were conducted with pupils (N=67) and teachers (N=5). The participants were grouped into three categories: low, medium and high anxiety, based on their scores. The results showed that 26% of the participants were assigned as low anxious learners; 59% of the students experienced medium levels of FLSA and 15% of the pupils were highly anxious language learners. Interviews with pupils and teachers explored the effects and the sources of the FLA and FLSA on pupils’ oral and general English language proficiency (fear of negative evaluation (FNE), affective variables, grades, teachers, classmates, pronunciation, and classroom atmosphere), noting that some pupils reported that monologic genres such as long episodes of speaking, evaluation situations and giving an oral presentation present the most anxiety-provoking contexts in EFL lessons.