Dendritic cells (DCs) play a central role in T-cell activation and the control of the inherent autoreactivity of the T-cell compartment. Pleiotropic DC functions are likely associated with discrete DC subsets. However, the latter remain largely defined by phenotype and unique anatomic location, rather than function. The investigation of DC involvement in complex phenomena that rely on multicellular interactions, such as immuno-stimulation and tolerization calls for an assessment of DC functions within physiological context. Given the highly dynamic DC compartment, the method of choice to study in vivo DC functions is their conditional ablation in the intact organism. Here, we summarize the recent progress in this field highlighting pitfalls and prospects of the approach.