A short conserved motif located at the carboxy terminus of FtsZ, referred to here as the CCTP (conservedcarboxy-terminalpeptide), is required for the interaction of FtsZ with many of its partners. InEscherichia coliinteraction of FtsZ with its membrane anchors, ZipA and FtsA, as well as the spatial regulators of Z-ring formation, MinC and SlmA, requires the CCTP. ZipA interacts with FtsZ with high affinity and interacts with the CCTP with low affinity, but the reason for this difference is not clear. In this study, we show that this difference is due to the oligomerization of FtsZ converting the CCTP to a multivalent ligand that binds multiple ZipAs bound to a surface with high avidity. Artificial dimerization of the CCTP is sufficient to increase the affinity for ZipAin vitro. Similar principles apply to the interaction of FtsZ with SlmA. Although donein vitro, these results have implications for the recruitment of FtsZ to the membranein vivo, the interaction of FtsZ with spatial regulators and the reconstitution of FtsZ systemsin vitro.