The business model (BM) has become a key concept in banking literature. The topic’s relevance is due to the impact of the crisis on bank profitability and risk levels, leading to new challenges for bank managers, analysts and regulators. The chapter deals first of all with the definition of BM in the management literature; afterwards the focus is on the on bank business model (BBM) and the business model analysis (BMA) literature, also considering the nexus with bank diversification. The point of view of supervisory authorities is critically analysed with specific regard of BMA embedded in the Supervisory Review and Evaluation Process (SREP).