The ultimate goal of research in Distributed Computing is to understand the nature, properties and limits of computing in a system of autonomous communicating agents. To this end, it is crucial to identify those factors which are significant for the computability and the communication complexity of problems. A crucial role is played by those factors which can be termed Structural Information: its identification, characterization, analysis, and its impact on communication complexity is an important theoretical task which has immediate practical importance. The purpose of the Colloquia on Structural Information and Communication Complexity (SIROCCO) is to focus explicitly on the interaction between structural information and communication complexity. The Colloquia comprise position papers, presentations of current research, and group discussions. Series 1 contains papers presented at the 1st Colloquium on Structural Information and Communication Complexity, held in Ottawa, Canada. Series 2 contains papers presented at the 2nd Colloquium held in Olympia, Greece.