Parallelism has been traditionally at the base of high-end complex platforms. In recent years, however, the emergence of novel technologies and computing systems has broadened considerably the spectrum of applications where parallel computation plays a fundamental role: on the one hand, chip manufacturers are shifting their focus towards new designs incorporating multiple cores within individual chips; on the other, large-scale networks are becoming the underlying infrastructures of innovative computing and data access platforms. Both traditional and emerging scenarios pose a number of challenging theoretical questions regarding architectures, models, and algorithmic strategies for effective parallel computing. Topic 12 is a suitable venue where researchers can discuss these questions and present their new achievements.