Instruction of T cell immunity is a key function of sentinel leukocytes called dendritic cells (DC). Several studies in mice and humans have demonstrated a key role for DCs in promoting T cell responses to cancer and augmenting the efficacy of T cell-based immunotherapies. Like other innate immune cells, DCs express a wide repertoire of receptors endowing them with the ability to detect microbial presence and tissue damage. These functions contribute to cancer immunity and have been previously linked to the induction of anti-tumour CD8 T cells and enhanced responses to immune checkpoint blockade (ICB) therapy. Here, I review some of the principles of DC biology, highlighting their functional characteristics that dictate T cell responses to cancer and how these can be harnessed in the design of novel immunotherapies.