Tumors are spatially organized ecosystems that are comprised of distinct cell types, each of which can assume a variety of phenotypes defined by coexpression of multiple proteins. To underscore this complexity, and move beyond single cells to multicellular interactions, it is essential to interrogate cellular expression patterns within their native context in the tissue. We have pioneered MIBI-TOF (Multiplexed Ion Beam Imaging by Time of Flight), a platform that enables simultaneous imaging of forty proteins within intact tissue sections at subcellular resolution. In this talk, I will describe our technological and computational advancements in multiplexed imaging, and demonstrate its application to study the tumor immune microenvironment in triple negative breast cancer and Melanoma. Our work reveals archetypical organizations, linking molecular expression patterns, cell composition and histology, which are predictive of patient survival.