In this paper, Distributed Spatial Modulation (DSM) is introduced. DSM is a cooperative diversity protocol for multirelay wireless networks, which is based on the concept of Spatial Modulation (SM). The distinguishable feature of DSM lies in improving the reliability of the source via distributed diversity and by increasing the aggregate throughput of the network, since new data is transmitted during each transmission phase. This is achieved by encoding the data transmitted from the source into the spatial positions of the available relays and by exploiting the signal domain for transmitting the data of the relays. At the destination, a diversity combiner that is robust to demodulation errors at the relays is proposed and its end-toend error probability and achievable diversity are studied. It is mathematically proved that DSM allows the source to achieve second-order diversity. With the aid of Monte Carlo simulations, DSM is compared against state-of-the-art cooperative protocols and it is shown to provide a better error probability.