We derive effective models from heterogeneous Cosserat media using asymptotic homogenization and taking into account size effects observed experimentally. The classification of the effective equations depends on the hierarchy of four characteristic lengths: the size of the heterogeneities ℓ, the Cosserat intrinsic lengths of the constituents ℓcoss and ℓchiral, and the overall characteristic length of the domain L. Depending on the different scale interactions between ℓcoss, ℓchiral, ℓ, and L we obtain either an effective Cauchy continuum or an effective Cosserat continuum with or without centrosymmetry. Herewith, we extend the work of Forest, Pradel, and Sab (Int. J. Solids Structures 38 (26–27): 4585–4608 ’01) by accounting for chiral effects.