AbstractImmunohistochemistry is an essential technique for the localization and measurement of proteins in cells and tissues. This article describes methods for labeling proteins in adherent and suspension cell cultures and in tissue sections. Choices of antibodies and detection methods are discussed, and detailed troubleshooting guidelines are provided. © 2022 Wiley Periodicals LLC.Basic Protocol 1: Immunofluorescent labeling of cells grown as adherent monolayersAlternate Protocol 1: Immunofluorescent labeling of cells in suspensionBasic Protocol 2: Immunofluorescent labeling of tissue sectionsAlternate Protocol 2: Immunofluorescent labeling using streptavidin‐biotin conjugatesAlternate Protocol 3: Immunofluorescent double‐labeling of tissue sectionsAlternate Protocol 4: Immunofluorescent double‐labeling of tissue sections with two primary antibodies from the same host species