In the mouse, cross‐presentation is an exclusive property of the CD8α⁺ subset of dendritic cells (DC) but the basis for this selectivity remains unclear. Here we report that splenic CD8α⁺ DC are much superior to other DC subsets in internalizing dying cells in vitro. In contrast, CD8α⁺, CD8α^– CD4⁺ and CD8α^– CD4^– DC subsets phagocytose bacteria or latex beads to a similar extent. Although CD8α⁺ DC are better than CD4⁺ DC at presenting ovalbumin (OVA)‐loaded splenocytes to naïve OT‐I T lymphocytes, CD4⁺ DC are better at presenting OVA‐expressing Escherichia coli to the same T cells. In both cases, presentation is abrogated by lactacystin. These results show that both splenic CD8α⁺ and CD8α^– DC can present exogenous antigens on major histocompatibility complex (MHC) class I via a proteasome‐dependent pathway and suggest that the specialized cross‐presenting function of CD8α⁺ DC is a result of their ability to endocytose dying cells rather than a unique pathway for handling endosomal contents.