We analyse cooperation within a company setting in order to study the external validity and consequences of a cooperative attitude. Around 450 employees of a large software firm participate in a fully incentivized online experiment. We observe very high levels of cooperation in a modified public goods game and the typical conditional cooperation patterns. When linking cooperation levels with individual decisions and outcomes within the company, cooperation in our experiment is predictive, for instance, for the receipt of appreciation awards. However, performance ratings are higher for more cooperative employees only in the sales division of the company. For the remaining employees, the relationship is significantly negative. More cooperative individuals also report a higher level of perceived stress. We analyse mechanisms that explain these results.