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Polymorphism is of great interest to the pharmaceutical industry because polymorphs have different physicochemical properties such as dissolution rate. In the present work, the influence of process conditions on the polymorphic antisolvent crystallization and transformations during cooling crystallization of agomelatine metastable form X from water/methanol solution has been investigated with a view of designing a robust process that includes not only crystallization but also filtration, filter cake washing, and drying. The competitive stability method was used in order to identify regions of the parametric space (water/methanol ratio, process temperature, and initial concentration) in which the crystallization of form X can be feasible. The formation of agomelatine form X was confirmed by subsequent kinetic experiments. The influence of process parameters such as the intensity of agitation, the antisolvent addition rate, and the precipitation temperature on the yield and particle size of the crystalline product was also investigated. The batch antisolvent crystallization of the metastable form X was monitored using in-line Raman spectroscopy and FBRM probe, and the type of the resulting polymorph has been confirmed by X-ray powder diffraction (XRPD). Finally, the effect of the obtained crystals of metastable form X on downstream operationsnamely, filtration and dryinghas been studied.