We generalize the coset procedure of homogeneous spacetimes in (pseudo-)Riemannian geometry to non-Lorentzian geometries. These are manifolds endowed with nowhere vanishing invertible vielbeins that transform under local non-Lorentzian tangent space transformations. In particular we focus on nonrelativistic symmetry algebras that give rise to (torsional) Newton-Cartan geometries, for which we demonstrate how the Newton-Cartan metric complex is determined by degenerate co-and contravariant symmetric bilinear forms on the coset. In specific cases we also show the connection of the resulting nonrelativistic coset spacetimes to pseudo-Riemannian cosets via Inönü-Wigner contraction of relativistic algebras as well as null reduction. Our construction is of use for example when considering limits of the AdS/CFT correspondence in which nonrelativistic spacetimes appear as gravitational backgrounds for nonrelativistic string or gravity theories.In view of their importance in nonrelativistic holography 2 , Lifshitz and Schrödinger spacetimes were already studied via coset constructions in [44] (and applied in e.g. [45-47]). Since nonrelativistic algebras are not semi-simple and have a degenerate Cartan-Killing metric, the standard (Riemannian) coset method of contracting the (inverse) vielbeins with the (inverse) Cartan-Killing metric, obtaining the metric and its inverse, does not apply. Instead of the Cartan-Killing metric, [44] uses the most general non-degenerate group invariant symmetric bilinear form, as [48] did for the Nappi-Witten WZW model on the non-semi simple group E c 2 , which is the centrally extended 2-dimensional Euclidean group. Thus [44] recovers the so-called Lifshitz and Schrödinger spacetimes, first proposed in [49, 50] and [51, 52], from a pseudo-Riemannian coset construction by performing cosets on the Lifshitz and Schrödinger groups respectively.However, aside from the somewhat counterintuitive concept of proposing locally relativistic spacetimes as duals to nonrelativistic field theories [34], difficulties with field profile reconstruction [53][54][55] as well as spacetime reconstruction [56] motivate the consideration of alternatives. As advocated in e.g. [25], such nonrelativistic spacetimes are more naturally viewed as Newton-Cartan spacetimes, described by a clock 1-form, degenerate spatial metric and an extra U (1) connection that contains the Newtonian potential. As we will see in this paper, the key observation is first of all that for certain choices of subgroup H ⊂ G the invariant bilinear form on the coset is necessarily degenerate. Consequently there are two (degenerate) distinct group-invariant bilinear forms on the coset: a covariant bilinear form (Ω ab ) and a corresponding dual bilinear form (Ω ab ). These objects are obviously not inverses of each other as they are both degenerate. With these two objects, we can construct the Newton-Cartan geometric data 3 for several interesting cases.Since some nonrelativistic algebras can be obtained using Inönü-Wigner contractions of relativi...