Infiltrating myeloid cells constitute a significant component of the suppressive tumor microenvironment (TME) and possibly contribute to therapeutic failures. An understanding of the immune regulatory context of the TME is required to harness the power of the antitumor immune response. Here, we present solutions to better understand the TME in a context-dependent manner. Using highly validated antibodies, immunohistochemical techniques are employed in a seven-color TSA-based multiplex panel along with single and dual-plex chromogenic stains to visualize biomarker expression in an array of tumor types. Thoroughly validated Arginase1 and IDO1 monoclonal antibodies add a functional readout of the immunosuppressive TME to phenotypic marker analysis.