This paper employs a mixed two-stage approach to estimate and explain differences in the cross-country efficiency of ten Australian, five UK and eight Canadian banks over the period 1988 to 2008 using stochastic distance, cost and profit frontiers. The first stage estimates efficiency scores for banks using a common frontier including uncontrollable environmental factors such as per capita national income, bank concentration, capital adequacy, deposit density and the average profit margin. The second stage investigates how controllable firm-specific factors help explain the differences in efficiency. In line with the experience of the banking sector during the recent global financial crisis, the evidence indicates that Australian banks exhibited superior efficiency. Key factors found to positively affect efficiency include intangible assets and the loans-to-deposits and loans-to-assets ratios. Key factors found to negatively affect efficiency include bank size, loan loss provisions, and financial leverage.