The staphylococcal superantigen-like proteins (SSLs) are a family of polymorphic paralogs encoded in the Staphylococcus aureus genome whose function is unknown. Here, we report crystal structure of SACOL0473 determined at 2.3 A resolution. The crystal structure of SACOL0473 was compared to other SSLs and that of a classical superantigen, streptococcal pyrogenic exotoxin. The ability of these secreted proteins to target antigen-presenting cells may enhance a misplaced antibody response against the proteins, which may facilitate bacterial colonization. Like classical superantigens, therefore, SACOL0473 may distract the host's immune system, but it may do so via entirely different molecular mechanism.