During brain disease, astrocytes can reprogram into a reactive state that alters many of their functions. Here, we present a protocol for studying neuroinflammation and reactive astrogliosis in mice using lipopolysaccharide (LPS) from E. coli. We describe steps for employing the Lcn2CreERT2 mouse crossed into a fluorescent Cre reporter line to label a subset of reactive astrocytes during and after inflammation. We then detail procedures for the longitudinal study of reactive astrocytes during the induction, progression, and/or resolution of astrogliosis. For complete details on the use and execution of this protocol, please refer to Agnew-Svoboda et al. 1 .