Proceedings of the Int. Workshop on Spatial Computing (SCW 2012) Many multiagent systems are spatial computers – collections of local computational devices distributed through a physical space, in which: • the interaction between localized agents is strongly dependent on the distance between them, and • the “functional goals” of the system are generally defined in terms of the system’s spatial structure. For example, spatial relationships are often used to organize the interactions between agents, at least in applications in which the problem and the space are intertwined. Furthermore, multiagent-based systems and their behaviors can be specified and analyzed relying on spatial notions like: location, region, frontier, neighborhood, obstruction, field, basin, communication, diffusion, propagation, etc. Systems that can be viewed as spatial computers are abundant, both natural and manmade. For example, in wireless sensor networks and animal or robot swarms, inter-agent communication network topologies are determined by the distance between devices, while the agent collectives as a whole solve spatially-defined problems like “analyze and react to spatial temperature variance” or “surround and destroy an enemy.” On the other hand, not all spatially distributed systems are spatial computers. The Internet and peer-to-peer overlay networks may not in general best be considered as spatial computers, both because their communication graphs have little relation to the Euclidean geometry in which the participating devices are embedded, and because most applications for them are explicitly defined independent of the network structure. Spatial computers, in contrast, tend to have more structure, with specific constraints and capabilities that can be used in the design, analysis and optimization of algorithms. The goal of the 5th Spatial Computing Workshop is to serve as an inclusive forum for the discussion of ongoing or completed work focusing on the theoretical and practical issues of explicitly using space in the design process of multiagent or multiactor systems. Indeed, the handling of space often remains implicit and elementary in general, reflected also in its limited adoption in the myriad of domain-specific programming languages. We believe that progress towards identifying common principles, techniques, and research directions—and consolidating the substantial progress that is already being made—will benefit all of the fields in which spatial computing takes place. And, as the impact of spatial computing is recognized in many areas, we hope to set up frameworks to ensure portability and cross-fertilization between solutions in the various domains. The Spatial Computing Workshop provides a premier forum for sharing both research and engineering results, as well as potential challenges and prospects.