Crystallization in the presence of pharmaceutically accepted excipients as additives was investigated as a tool for morphological crystal engineering of active pharmaceutical ingredients. Recrystallization of a model drug substance, erythromycin A dihydrate, was carried out by a precipitation technique in the presence of varying amount of hydroxypropyl methylcellulose (HPMC). In contrast to the reference crystals, the crystals grown in the presence of HPMC exhibited regular shape, which varied with the concentration of the additive present, thus indicating that HPMC is an effective habit modifier for erythromycin A dihydrate. On the basis of the crystal surface chemistry, the mechanism responsible for the change in morphology is proposed. Finally, the effect of crystal habit modification on compaction behavior of erythromycin A dihydrate is demonstrated.