The European Workshop on Software Ecosystems is an annual event which connects researchers and fellow professionals in the field of software ecosystems. Presentations in 2015 included: Jon Scott, SVP Corum - Keynote Software M&A Ecosystems, Stefan Henningson, Copenhagen Business School - Cisco is using acquisitions of software companies to re-invent its "platform core", Andreas Schönberger, Siemens AG - Using ecosystem modeling to drive ecosystem projects, Abilio Avila, Orestis Terzidis, Karlsruhe Institute of Technology (KIT) - Management of Partner Ecosystems in the Enterprise Software Industry, Alexander Serebrenik, Technical University of Eindhoven - Surveying Challenges in Software Ecosystems Research, Ralf Meyer, Synomic GmbH - Why even successful large Software Ecosystems need professional representation like International Association for SAP Partners, Jonathan Hildenbrand, Netfira - Keynote Business networks, Sami Hyrynsalmi, University of Turku - To Redefine Ecosystem Health, or not to Redefine? A view of scientific knowledge on the "software ecosystem health" concept, Dominik Dellermann, Alexander Fliaster, University of Bamberg - The Strategic Risks of Software Ecosystems, Christopher Jud, Georg Herzwurm, University of Stuttgart - Platforms and ecosystems from complementers' point of view.