Sips: shift-and-invert parallel spectral transformations. SIPs is a new efficient and robust software package implementing multiple shift-and-invert spectral transformations on parallel computers. Built on top of SLEPc and PETSc, it can compute very large numbers of eigenpairs for sparse symmetric generalized eigenvalue problems. The development of SIPs is motivated by applications in nanoscale materials modeling, in which the growing size of the matrices and the pathological eigenvalue distribution challenge the efficiency and robustness of the solver. In this article, we present a parallel eigenvalue algorithm based on distributed spectrum slicing. We describe the object-oriented design and implementation techniques in SIPs, and demonstrate its numerical performance on an advanced distributed computer.