During last years, ICTs have enabled the rise of the so-called “collaborative consumption” (CC) – a form of consumption where people share goods and services online. CC has been expected to alleviate societal problems such as hyper-consumption, pollution, and poverty by lowering cost of economic coordination within communities. However, beyond anecdotal evidence, there is a dearth of understanding why people participate in CC. Therefore, in this paper we investigate people’s motivations to participate in CC. The study employs survey data (N=168) gathered from people registered into a collaborative consumption site. The results show that participation in collaborative consumption is motivated by many factors such as its sustainability, enjoyment of the activity as well as economic gains. An interesting detail in the result is that sustainability is not directly associated with participation unless it at the same time is also associated with positive attitudes towards CC. This suggests that sustainability might only be an important factor for those people for whom ecological consumption is important. Furthermore, the results suggest that in CC an attitude-behavior gap might loom; people perceive the activity positively and say good things about it, but this good attitude does not necessary translate into action.