Reading proficiency is particularly crucial for adolescent students who are expected to adopt and approximate a multitude of authentic literacy practices in several different content areas within the span of a single school day. A large number of adolescent students are failing to master basic levels of reading, and are thus uniquely disadvantaged in secondary schools, where reading is not only more complex, but teachers also spend less time teaching students how to read. Reading motivation has been a focus of research to address the lack of reading proficiency in classrooms. An understudied area within this field of research is the effects of the learning environment on student reading motivation (Neugebauer & Gilmour, 2020). The current study investigates the effects of student perception of the learning environment on their self-reported reading motivation in four different content areas (English, social science, math, science) at a large, public high school in the San Francisco Bay Area. Students took a daily reading motivation measure to capture their unique motivations within different content areas, as well as a measure of their perception of the learning environment. Four different aspects of the learning environment, "teacher support," "student cohesiveness," "involvement," and "investigation," were regressed on student reading motivation, which was comprised of two variables: "reading involvement" and "reading curiosity." For all content areas and for both "reading curiosity" and "reading involvement" as dependent variables, the only learning environment variable to significantly predict reading motivation was "investigation." "Investigation" refers to the extent of emphasis placed on problem-solving and inquiry in the classroom and falls under the personal growth category of learning environment dimensions (den Brok et al., 2010). The more perceived emphasis placed on investigation in all content areas, the more students felt individually motivated to read in that content area. This finding suggests that teachers can potentially maximize students' motivation to read by introducing more investigation into their classrooms. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]