Salts and polymorphs of a compound useful in the treatment of inflammatory and metabolic conditions and diseases are provided herein. In particular, the invention provides salts and polymorphs of a compound which modulates the expression and/or function of a peroxisome proliferator-activated receptor. The salts and polymorphs are useful for the treatment or prevention of conditions and disorders associated with energy homeostasis such as type II diabetes, lipid metabolism, adipocyte differentiation and inflammation.