This special issue collects research from many of the leaders in both the application and the theory of productivity and inefficiency. We started this special issue prior to the COVID-19 pandemic, and with individuals and firm shaving to adapt on the fly to lockdowns, social distancing, masking and the perils of operating in a nonstandard environment, both understanding the presence of (in)efficiency and how to improve productivity have taken on heightened importance.Firm-level technology and productivity are key inputs to models in many fields including trade, labor, environmental economics, industrial organization, financial economics as well as management, rendering the measurement of efficiency and productivity impact across many different areas beyond just microeconomic analysis of the firm. This field is constantly evolving as new approaches are developed and implemented on a near weekly basis. For evidence of this look, no further than the biannual conferences run in Europe, North America and the Pacific Rim which routinely host myriad "methods" and "applications" sessions where leading scholars discuss cutting-edge techniques and their empirical applications targeted at solving outstanding issues across many fields of economics, operation research, engineering, etc.Our aim with this special issue of Empirical Economics is to bring together contributions both from the preeminent experts actively working on the development of new and robust methodologies for the measurement of efficiency/productivity as well as r -Certified Random.