Background: Previous literature highlights the importance of causal attributions in achievement and motivation. However, the studies about causal attributions in second language acquisition (SLA) are limited and scarce. Aims: This study was designed to determine the frequency of successful and unsuccessful activities per English level and to compare the causal attributions (explanations of outcomes) on successful and failure authentic tasks undertaken in the context of learning English as a foreign language (EFL) acquisition in an Official School of Languages (OSL).SampleTo this aim, 407 native Spanish students from levels A1 (n = 111), A2 (n = 113), B1 (n = 98), and B2 (n = 85) in OSL participated in this study. Method: Participants completed Attribution to Success and Failure Questionnaires (ASQ & AFQ). Results: Results of ANOVAs and Scheffe "post hoc" test show main significant differences between A1 and B2 students. Students at A1 level perceive their success in the foreign language (FL) as dependent on some internal but unstable controllable variables, such as effort and strategy, and to some external variables such as teacher influence, task difficulty, and class atmosphere. On the contrary, students at B2 level perceive that their successful outcomes in FL depend on ability, marks, class level, preparation, and enjoyment within the classroom, whereas they perceive that their failure outcomes are dependent on external factors such as luck, teacher influence, and/or task difficulty. Conclusions: Results provide evidence that students from OSL employ multiple causal attributions to explain their academic success and failure, which may also have educational implications for class teachers.