This special issue of Soft Computing is dedicated to several aspects of complex systems, with particular attention to evaluation and decisional procedures, risk analysis, application to many fields in socio-economical areas.

The papers have been selected among the contributes presented at Dyses 2018 Conference held at the Sorbonne during October 2018, focused mainly on systemic risk and complex systems.

The range of topics, methods and domains is truly wide.

There are several scientific results dedicated to decision procedures as MCDM methods, game theoretic approach or Choquet capacities, with specific applications as climate change, pollution and other issues of interest for the environment.

The analysis of markets has been carried on, by considering, by means of innovative tools, important issues as risk factors, efficiency, stability, duopolistic competitions.

Many authors, also in dynamical contexts, have faced with optimization problems.

Contributes to Network analysis has been supplied: this is another very useful approach to complexity; agent interaction in complex systems and relations with systemic shock propagation are considered.

Some financial issues as behavior of prices, and interest rates, as far as the tools for managing with uncertainty and ambiguity are considered; many contributes are dedicated, for instance, to wide domain of Data analytics, Fuzzy set, Many valued logics.

We are sure that the interdisciplinary approach is the best way to understand and manage with complex systems.

As guest editors, we would like to thank all the Authors and Soft Computing for giving us the opportunity to publish this special issue.