This paper presents the results of a European benchmark on multiscale creep modeling for cementitious materials, performed in the framework of the COST Action TU1404 "Towards the next generation of standards for service life of cement-based materials and structures". Three micromechanical models from three research groups have been adopted for modeling the basic non-aging creep of cementitious materials. The benchmark is based on the hypothesis that creep results only from calcium-silicate-hydrates (C-S-H) and that viscoelastic behavior of all microstructural constituents are maturity-and composition-independent. By comparing model results among themselves as well as by comparing model predictions with experimental results obtained from three different laboratories, we demonstrate that creep upscaling from micrometer-sized C-S-H to centimeter-sized macroscopic samples of cement paste, mortar, and concrete, and from minutes-long creep tests at early ages to days-long creep tests at very mature ages is indeed possible. The benchmark also highlights the importance of considering micro-anisotropy of C-S-H in terms of nonspherical shapes for C-S-H hydrates.