Holonomic and semi-holonomic geometries modelled on a homogeneous space $G/P$ are introduced as reductions of the holonomic or semi-holonomic frame bundles respectively satisfying a straightforward generalization of the partial differential equation characterizing torsion–free linear connections. Under a suitable regularity assumption on the model space $G/P$ we establish an equivalence of categories between Cartan geometries and semi-holonomic geometries modelled on $G/P$.