I build a model of technology adoption to study the quantitative effect of entry barriers on total factor productivity (TFP). In my model, incumbent firms choose technologies that are sufficiently productive to deter entry from a potential competitor. I show that higher entry barriers help to deter entry and lead to the choice of less productive technologies. A novelty of my work is that I use a direct measure of entry barriers. I find that reducing entry barriers from their average level in the poorest 30% of countries to their U.S. level leads to a sizeable increase in aggregate TFP of 12%. (JEL O11, O43)