The present invention encompasses antagonist anti-CD40 antibodies and antigen-binding portions thereof. Specifically, the invention relates to humanized anti-CD40 antibodies. In certain embodiments, antibodies of the invention neutralize human CD40 (hCD40) activity. Antibodies, or antibody portions, of the invention are useful for detecting CD40 and for inhibiting CD40 activity, e.g., in a human subject suffering from a disorder in which CD40 activity is detrimental.