Within elementary science reform, time is a crucial consideration, yet conceptions of time in education research are undertheorized. To address this gap, we use sociological literature to identify three conceptions of time that help us understand and interpret leaders' and teachers' sensemaking and decision making about time in their efforts to improve elementary science education and use national survey data to uncover systems' time-focused decisions related to elementary science. Drawing on data from 13 US educational systems that were working to improve elementary science, we present three cases to illustrate how leaders' decisions, collectively, constitute dilemmas for which there are no easy solutions. We construct an expansive conceptual framework of time in educational systems' decision making, showing how the typical conception of time as objective and limited is, itself, limited, and that conceptions of time as political and organizational time round out an understanding of system actors' sensemaking and the dilemmas therein.