This study seeks to understand student attitudes towards English for Specific Purposes (ESP) courses. Such courses were conceived, in part, under the belief that they would be inherently more motivating as they, ideally, correspond directly to students’ interests and needs. Rather than accepting this notion at face value, this paper posits that a thorough analysis of student behaviours and attitudes in ESP courses is required to fully understand their effectiveness in terms of their capacity to motivate students. To do so, this paper suggests studying motivation through the lens of the Complex Dynamic Systems Theory (CDST). This theory allows for the analysis of motivation as a dynamic phenomenon, strongly dependent on all the factors present in a given system, namely, a language classroom. Questionnaires, interviews, and observation data were used to analyse student motivation in English for Arts and General English (GE) courses at a large, public university in France. Results indicate that students were mostly indifferent to the specialised elements of their language courses and that their motivation was more dependent on the structure of different activities.