Three-dimensional structures of S100B, S100A1, S100A6 and S100A11 have shown that calcium binding to these proteins results in a conformational change allowing them to interact with many biological targets. The structures of some S100 proteins in the presence of peptide targets from Ndr kinase, p53, CapZ, annexins A1 and A2 and the Siah-1 Interacting Protein indicate there are at least three modes of recognition that utilize two distinct surfaces in the S100 proteins. These surfaces have been hypothesized to simultaneously accommodate multiple binding partners. This review focuses on potential multiprotein complexes involving calcium-insensitive S100A10, annexin A2 and several other proteins including AHNAK, dysferlin, NS3, TASK-1 and TRPV5/6.