The present invention is directed to antibodies and binding fragments thereof, which bind with high affinity and specificity to human P-selectin glycoprotein ligand 1 (PSGL-1) and which block both selectin and chemokine binding to PSGL-1 expressed on leukocytes, lymphocytes and endothelial cells and thus which inhibit migration and/or rolling of these cells and to methods for screening for such antibodies and binding fragments thereof and to methods of therapeutic use thereof.