Crowdsourcing enables new possibilities for QoE evaluation by moving the evaluation task from the traditional laboratory environment into the Internet, allowing researchers to easily access a global pool of subjects for the evaluation task. This makes it not only possible to include a more diverse population and real-life environments into the evaluation, but also reduces the turn-around time and increases the number of subjects participating in an evaluation campaign significantly by circumventing bottle-necks in traditional laboratory setup. In order to utilise these advantages, the differences between laboratory-based and crowd-based QoE evaluation must be considered and we therefore discuss both these differences and their impact on the QoE evaluation in this chapter.