The citrate salt of (S)-4-(4-Chloro-phenyl)-1-{3-[7-(1-hydroxy-1-methyl-ethyl)-11H-10-oxa-1-aza-dibenzo[a,d]cyclohepten-5-ylidene]-propyl}-3,3-dimethyl-piperidin-4-ol, which may be used in pharmaceutical applications, is disclosed. The crystalline Citrate Salt, including particular single crystal forms and combinations of the single crystalline forms, are also discussed. Mixtures for forming the crystalline salts are discussed. As well, methods of producing the Citrate Salt, and crystalline forms thereof, and using such Citrate Salt, and crystalline forms thereof, in treating diseases associated with aberrant leukocyte recruitment, activation, or recruitment and activation are also discussed.