In vivo, cells exist within a complex mixture of glycoproteins and proteoglycans termed the extracellular matrix (ECM). The components of the ECM are secreted by the cells in that site, and the ECM provides not only a physical support but also outside-in signals that regulate many cellular functions, including cell proliferation, differentiation, migration, and survival. Altering the composition of the ECM can thus significantly alter cell behavior. Many types of cells, including normal and malignant epithelial and mesenchymal cells, secrete galectin-1, a member of the galectin family of lectins, into the ECM surrounding the cells. Galectin-1 is known to regulate many of these same cellular functions (i.e., proliferation, differentiation, migration, and death), so that the presence of galectin-1 in ECM will modify the effects of ECM on cells. In this chapter, we present three types of assays that allow interrogation of the effects of galectin-1 on cell adhesion to ECM, cell migration through ECM, and cell death in ECM, using T-cell lines as a model cell type.