One puzzle concerning highly idealized models is whether they explain. Some suggest they provide so-called 'how-possibly explanations'. However, this raises an important question about the nature of HPEs, namely what distinguishes them from 'normal', or how-actually, explanations? My paper purports to provide an account of how-possibly explanations that clarifies their nature in the context of solving the puzzle of model-based explanation. I argue that the modal notions of actuality and possibility provide the relevant dividing lines between how-possibly and how-actually explanations. My proposal both contributes to the literature on the puzzle of model-based explanation and, more generally, to the literature on how-possibly explanations.