Reactions of calcium bromide with enantiopure and racemic proline in aqueous solution lead to two solids in which the zwitterionic amino acid acts as a bridging ligand between neighbouring cations. Depending on the chirality of the amino acid, topologically very different products are obtained. With racemic proline, bromide acts as a simple uncoordinated counter‐anion for the cationic heterochiral chains in catena‐poly[[aquacalcium(II)]‐μ‐aqua‐μ3‐DL‐proline‐μ2‐DL‐proline], {[Ca(C5H9NO2)2(H2O)2]Br2}n. In agreement with chemical intuition, only carboxylate and aqua O atoms coordinate the alkaline earth cation in a low‐symmetry arrangement. In contrast, L‐proline affords the two‐dimensional network poly[dibromidobis(μ2‐L‐proline)calcium(II)], [CaBr2(C5H9NO2)2]n, with an unexpected CaBr2 unit in a more regular coordination sphere.