This paper presents findings from a larger study that examined the roles that parents and caregivers are given and/or choose to enact to support their children's mathematics learning, particularly in relation to their children's math homework. Based on interviews with parents of elementary-age children from three different urban school districts in the northeastern United States, we propose a conceptualization of parental engagement that uses a framework of human agency to understand both beliefs and rationales underlying parental actions as well as the apparent lack of actions. Our findings identify challenges parents encounter in relation to their children's school mathematics and reveal the limits of school-centered conceptions of parental engagement. (Contains 2 tables.)