This paper reports on the growth of benzamide crystals in the presence of 2′-aminoacetophenone. The resulting self-replicating intergrowth of benzamide crystals gives rise to ordered crystal aggregates in which individuals share a common c*. This behavior is interpreted using the concept of a "motif capper" additive which is able to halt the extension of structural motifs at the surface of a growing crystal. In this case the additive was selected to terminate the hydrogen-bonding ribbons, which extend along the b axis of the benzamide structure. © 2005 American Chemical Society.