Ecological processes occur over a multitude of scales. These scales may be spatial (centimeters versus kilometers), temporal (days versus years), or ecological (individuals versus ecosystems). When important interactions occur across these scales, outcomes at one level may be drastically impacted by outcomes at another level. Because of this, explaining population-level outcomes often requires that we disentangle the effects of interactions across one or more of these scales. Isolating the effects of these interactions may be difficult or even impossible in practice. However, mathematical models which provide detailed descriptions of interactions across scales can improve our understanding of ecosystems. In this mini-symposium, we highlight work studying four different systems, in which ecological interactions at multiple scales impact a population of interest. The speakers use models across different scales to describe these interactions and provide valuable insight into a range of application-level questions. At the same time, their methodologies highlight the challenges associated with modelling interactions across scales. Such interactions are necessarily complex, leading to challenges in analysis, parameterization, and simulation of the resulting models. This minisymposium will provide a timely opportunity for researchers to compare the practical uses and limitations of ecological models across multiple scales.