Linear contracts are simple to analyze, are observed in some real-world settings, and have an appealing property: they create uniform incentives, in the following sense. Think of output, y, as aggregate output over (say) a year, but think of the Agent as taking lots of little actions over the course of the year—such as one per day. A non-linear contract may create unintended or unhelpful incentives over the course of the year, depending on how the Agent has done so far.