The present invention relates to methods of treating or preventing cancer and other diseases using molecules, particularly polypeptides, more particularly immunoglobulins (e.g., antibodies), comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds an FcγR that activates a cellular effector (“FcγRActivating,” such as FcγRIIA or FcγRIIIA) and an FcγR that inhibits a cellular effector (“FcγRInhibiting,” such as FcγRIIA) with an altered Ratio of Affinities relative to the respective binding affinities of such FcγR for the Fc region of the wild-type immunoglobulin. The methods of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection where either an enhanced efficacy of effector cell function mediated by FcγR is desired (e.g., cancer, infectious disease) or an inhibited effector cell response mediated by FcγR is desired (e.g., inflammation, autoimmune disease).