The structures of two arylsulfonamide para-alkoxychalcones, namely, N-{4-[(E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C22H19NO4S, (I), and N-{4-[(E)-3-(4-ethoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C23H21NO4S, (II), reveal the effect of the inclusion of one -CH2- group between the CH3 branch and the alkoxy O atom on the conformation and crystal structure. Although the molecular conformations and one-dimensional chain motifs are the same in both structures, their crystallographic symmetry, number of independent molecules and crystal packing are different. The crystal packing of (I) is stabilized by weak C-H...π and π-π interactions, while only C-H...π contacts occur in the structure of (II). The role of the additional methylene group in the crystal packing can also be seen in the fact that the alkoxy O atom is an acceptor in nonclassical hydrogen bonds only in the para-ethoxy analogue, (II). The remarkable similarity between the crystal packing features of (I) and (II) lies in the formation of N-H...O hydrogen-bonded ribbons, a synthon commonly found in related compounds.