© 2022 Elsevier LtdThis paper focused on the endogenous and exogenous factors affecting the performance of small and medium-sized Turkish airports. A two-stage approach was adopted. Non-radial DEA methodology was applied in the first step to define the specific endogenous sources in the resource utilization, output production, and revenue generation processes. Shannon's entropy was employed to capture the homogeneity in the endogenous performance drivers. Exogenous sources of efficiency were defined in the second step. Results showed that inefficiency in Turkish airports is mainly driven by endogenous sources, where runway utilization and non-aeronautical revenue generation are the main reasons. Policy implications were derived.