In this presentation I will discuss how prior reading experience and assessment influence the level of agency learners feel when part of an extensive reading programme, using the lens of Activity Theory (Galperin, 1969). Activity Theory takes the position that human activities should be understood as systemic and socially situated. For example, the extensive reading approach argues for learners selecting their own reading material and reading at their own pace (Day and Bamford, 2002). However, little is known about the factors that influence learners' reader selection and how students engage with graded readers, as a socially situated and systemic activity. The data in this presentation is taken from interviews with seven participants in an extensive reading programme at a private university in central Taiwan at three stages of the second semester (beginning, middle and end). Data was transcribed and coded for themes. Findings reveal that prior experience reading in English, selecting appropriate reading material and assessment negatively affect the agency learners feel they have when engaged in an ongoing cycle of selecting reading material and poring over text.