This article examines bank lobbying in the Basel Committee on Banking Supervision (BCBS). While excessive bank lobbying is routinely linked to weakened banking regulations, we still know little about bank mobilization patterns. In particular, when and why do some banks lobby the BCBS while others do not? I argue that the decision to lobby is a function of two factors: banks’ organizational characteristics and domestic banking regulations. I test my argument using a unique dataset of over 33,000 banks worldwide during the period in which the Basel III Accord was negotiated. My findings confirm a pronounced bias in bank mobilization patterns toward wealthy, internationally active banks. I also find that banks facing more stringent banking regulations at home tend to lobby the BCBS in an effort to level the playing field with international competitors. This effect is particularly salient for stringent regulations on banking activities as well as higher capital adequacy requirements.