We construct an extension of the Poincaré group which involves a mixture of internal and space-time supersymmetries. The resulting group is an extension of the superPoincaré group with infinitely many generators which carry internal and space-time indices. It is a closed algebra since all Jacobi identities are satisfied and it has, therefore, explicit matrix representations. We investigate the massless case and construct the irreducible representations of the extended symmetry. They are divided into two sets, longitudinal and transversal representations. The transversal representations involve an infinite series of integer and half-integer helicities. Finally, we suggest an extension of the conformal group along the same line.