L-selectin (CD62L) amplifies neutrophil capture within the microvasculature at sites of inflammation. Activation by G-protein coupled stimuli or through ligation of L-selectin promotes clustering of L-selectin and serves to increase its adhesivity, signaling, and colocalization with ₂-integrins. Currently, little is known about the molecular process regulating the lateral mobility of L-selectin. Upon neutrophil stimulation, a progressive change takes place in the organization of its plasma membrane, resulting in membrane domains that are characteristically enriched in glycosylphosphatidylinositol (GPI)-anchored proteins and exclude the transmembrane protein CD45. Clustering of L-selectin, facilitated by E-selectin engagement or antibody crosslinking, resulted in its colocalization with GPI-anchored CD55, but not with CD45 or CD11c. Disrupting microfilaments in neutrophils or removing a conserved cationic motif in the cytoplasmic domain of L-selectin increased its mobility and membrane domain localization in the plasma membrane. In addition, the conserved element was critical for L-selectin-dependent tethering under shear flow. Our data indicate that L-selectin's lateral mobility is regulated by interactions with the actin cytoskeleton that in turn fortifies leukocyte tethering. We hypothesize that both membrane mobility and stabilization augment L-selectin's effector functions and are regulated by dynamic associations with membrane domains and the actin cytoskeleton.