Eosinophils are prominent in allergic diseases, and their effector functions are studied in numerous gene-deleted and transgenic mouse models. However, mouse eosinophils and human eosinophils are not structurally or functionally equivalent, and assays designed to evaluate the properties of human eosinophils may or may not be reliable or effective in experiments targeting their murine counterparts. In this chapter, we emphasize methods focused on detection, isolation, and functional assessment of eosinophils from mouse tissue and present a protocol that promotes the growth and differentiation of eosinophils from unselected mouse bone marrow progenitors. Overall, these protocols provide a scaffold on which the relative contributions of mouse eosinophils can be evaluated.