Drawing on the concept of agency and teacher agency and engaging with figurational sociology, this paper explores the extent to which teacher agency plays a role in one teacher's enactment of a new school subject (Leaving Certificate Physical Education (LCPE), an examinable subject assessed in a high-stakes environment) in a period of curriculum change and reform in Irish post-primary schools. Through a case study design, one teacher was interviewed regularly (19 times) during their 1st year of teaching LCPE. The findings are presented in three teaching episodes. In analysing the three teaching episodes, the process (and fluctuation) of achieving agency is evident. The achievement of agency should not be conceptualised as a product (achieved) but rather, it should be viewed as something that is processual (achieving). We offer a figurational viewpoint of teacher agency through a constructed Figure in the paper. We argue that it is impossible to link the achievement of agency with one element (including the teacher). It is the combination of interdependent relationships (past and present, recognised and unrecognised) in a teacher's figuration, the overarching social processes, and the contextual and structural factors surrounding and within a figuration. The paper provides considerations in how best to support teachers in their process of achieving agency.