The present disclosure provides a crystalline form of grapiprant selected from the group consisting of Form X, Form X2, Form X3, Form F, Form K, Form L, Form M, and Form N. Also provided is a pharmaceutical composition, the composition comprising at least one crystalline form of grapiprant, and at least one pharmaceutically acceptable excipient, wherein the crystalline form of grapiprant is selected from the group consisting of Form X, Form X2, Form X3, Form F, Form K, Form L, Form M, and Form N. Other aspects of the disclosure provide a process for preparing a substantially pure crystalline Form A of grapiprant. The process comprises contacting grapiprant at ambient temperature with a solvent comprising dichloromethane and acetone to form a saturated or a near saturated solution. Crystals of the substantially pure crystalline Form A of grapiprant are formed.