Although research on boredom in second language (L2) learning contexts has garnered increasing attention, boredom as a negative emotion remains largely uncharted in EFL settings. Previous research has not thoroughly delved into specific categories of factors responsible for boredom in the English language classroom. Therefore, this study explores this construct, honing in on antecedents pertinent to learning content, materials, and in-class tasks. Adopting a quantitative approach, a comprehensive 35-item composite questionnaire was developed drawing on well-established models and theories of boredom to elicit responses from English majors (n = 310) at a university in Saudi Arabia. The data underwent rigorous statistical analysis employing various techniques. The principal components analysis reveals a constellation of five factors associated with the experience of L2 boredom: (1) Tedious task, (2) Irrelevant content, material, and task, (3) Task repetitiveness and a lack of output, (4) Content and task difficulty as well as divergence from learner needs, and (5) Monotonous and unsupportive content. Furthermore, the findings shed light on the effect of perceived L2 proficiency on the instigation of L2 boredom. This study concludes with pedagogical implications and potential avenues for research in this area.