Astrocytes’ perivascular processes (PvAPs) entirely sheathe the brain’s blood vessels and are equipped with an enriched molecular repertoire that sustains astrocytic regulatory functions at the vascular interface. We recently demonstrated that PvAP development in the mouse starts after birth and is essentially complete by postnatal day (P) 15. This time window also corresponds to a progressive molecular maturation of PvAPs with the acquisition of specific proteins. We proposed local translation of mRNAs in PvAPs as a molecular mechanism participating to their development and maturation. Here, we describe methods to quantify the development of PvAPs and detect local translation in developing PvAPs. We also show how to analyze quantitatively astrocytic-specific mRNAs and polysomal mRNAs in developing PvAPs. These experimental approaches allow to characterize important aspects of the dynamic postnatal development and molecular maturation of PvAPs.