Purpose: This paper aims to apply ecological models of agency to understand factors influencing how an eighth grade English language arts (ELA) teacher enacted agency in four moments in the classroom. It focuses on how his language in relation to his instructional choices reflected messaging to his students regarding the learning he intended from his ELA instruction. Design/methodology/approach: The paper applies an existing framework (Biesta "et al.," 2015, 2017), adding Bakhtin (1981) understandings of language, to classroom discourse supplemented by teacher interviews and other data sources. In looking across these data sources, the paper traces the influence of past factors (i.e. the teacher's personal and professional history) and future orientations (i.e. goals established in standards and the teacher's goals for his students) on present instructional decisions. The teacher's language in the classroom becomes a primary focus for this study, as it reveals the ways in which he drew on specific resources in the messages in his instruction. Findings: In each moment, the teacher's language could be shown to have motivation in a variety of factors. While influenced by external factors such as the common core standards and standardized assessments, the teacher often enacted agency out of his personal beliefs about making learning personally meaningful for students as grounded in his personal and professional history. Exceptions to this pattern, especially regarding preparing students for writing tests on state assessments, less frequently relied on the language of finding meaning in the learning. Originality/value: This paper builds on studies of ELA teacher agency through the development of methodology related to an ecological model of agency and Bakhtinian concepts of language focused on the discourse of the classroom. It contributes to understanding the factors at study in an ELA teacher's instructional agency, which can help teachers and researchers further develop frameworks for describing and assessing the practice of agency in the profession.