This study uses a stochastic frontier analysis (SFA) model to evaluate the relative cost efficiency of commercial banks in Taiwan in the wake of liberalization. The model is estimated using data made available through Taiwan's Banking Bureau and Financial Supervisory Commission. With data from before and after the 2008 financial crisis, our central result is that banks affiliated with bank holding companies (BHC) have become increasingly more efficient. While unaffiliated banks have generally increased their efficiency, they have not kept pace with respect to efficiency gains. Secondary findings are that, independent of ownership structure, both balance sheet and income statement composition affect efficiency. In particular, bank efficiency increases with growth in loans and capital prices. We also find evidence that labor productivity is a key explanatory factor behind efficiency differences across banks. As a result, a policy recommendation is made that banks invest in maximizing worker productivity. Finally, in addition to the insights gained from this study we contribute to the general literature on both bank efficiency and the use of the SFA model by applying it to new data in a new setting.