The crystallization of 2,6-di(propanoylamino)pyridine ([CH3(CH2)(n-1)CONH](2) C5H3N, n = 2, [2Apy]) from hexane/ethyl acetate mixed solvent gives two types of crystals, 2APy and 2Apy center dot 2H(2)O. The crystal data, packing structures, and hydrogen bonding network of both crystals suggest that 2APy and 2APy center dot 2H(2)O are not structurally similar. In the crystal structure analysis of 2APy, two crystallographically independent 2APy molecules were observed in its asymmetric unit, whereas the asymmetric unit of 2APy center dot 2H(2)O consists of one crystallographically independent 2APy molecule and two crystallographically independent water molecules (Ow, Ow'). The water molecules (Ow, Ow') are connected via Ow center dot center dot center dot Ow' intermolecular hydrogen bonds to form two chains in a one-dimensional arrangement along the direction of c -axis, built up of two crystallographically independent water molecules. The driving force behind the molecular aggregation of 2APy is mainly N center dot center dot center dot O = C hydrogen bonding, whereas those of 2APy center dot 2H(2)O are N center dot center dot center dot Ow, C = O center dot center dot center dot Ow, and Ow center dot center dot center dot Ow' hydrogen bonding. The differences in the kind of hydrogen bonding networks in both crystals contribute to the differences in the packing modes observed in 2APy and 2APy center dot 2H(2)O.