In the peak of the summer 2013, between the 7th and the 9th of August, the workshop "25 Years of Combining Compositionality and Concurrency" took place in Königswinter, a picturesque little town overlooking the Rhine river, in the outskirts of Bonn. The event, organised by Ursula Goltz, Rob van Glabbeek and Ernst-Rüdiger Olderog, was meant to celebrate and revisit, a quarter of a century later, the workshop "Combining Compositionality and Concurrency" (CCC88) that had been held in March 1988 in the same hotel, the Loreley, on the initiative of the same trio of researchers (the first two of which were still PhD students at the time). Both workshops were by invitation only, and each attracted 34 participants. Because of its timely character and its deliberate focus on bridging the gap be-tween process calculi and "true-concurrency" models, the original CCC88 workshop, targeting a group of active researchers from both fields, had generated much enthusiasm and discussion. It had therefore gradually acquired, at least in the memories of its participants, the mythical status of a "foundational event". It was then quite natural for the organisers, 25 years later, to envisage a kind of jubilee event, which could bring together a number of participants from the original workshop, as well as younger researchers who had joined in more recent years the field of concurrency theory, now much broader and well-established.