There have been recent calls to support student agency in the field of literacy. Agency, which we define in the context of schooling, is a multidimensional construct where individuals exert influence and create opportunities in the learning context through intentions, decisions, and actions. We propose highlighting agency as an interconnected construct, which includes self-perception as readers and writers, intentionality, choice-making, persistence, and interactiveness. Elementary students (n = 1,726) completed surveys of their agency along with standardized literacy assessments. Statistical analyses largely aligned with the hypothesized dimensions of agency. Relationships to student literacy achievement were stronger in grades 3rd-5th than in 1st-2nd grades. Discussion highlights how elementary students have a voice in their agency as it pertains to literacy. Implications for future research and practice are discussed.