Children’s educational aspirations have been shown to be highly relevant for their educational trajectories and, therefore, researchers have tried to understand how and when these aspirations are formed. The influence of parental aspirations on the development of children’s aspirations has often been the focus of such investigations in previous studies. Going beyond these earlier approaches, we address the question of how children’s aspirations might be influential for their parent’s aspirations. We also investigate if it is children’s perception of parental aspirations or parent’s factual aspirations, which play a role in the formation of children’s aspirations. This article contributes to the literature, first, on a theoretical basis, by providing a reasoned and interdisciplinary framework about mutually dependent processes of aspiration formations within families. Second, an empirical contribution is given, using data from the German National Educational Panel Study and analyzing the aspirations of 4,511 children and their parents. Our cross-lagged panel models show that children and parents influence each other in their aspirations mutually over time, with children being affected by both, the parent’s factual aspirations and the children’s perception of those. We give empirical-driven guidelines for future research on aspiration formation.