Young researchers in the field of operations research from all of Europe met at the Johannes Kepler University Linz from July 16th to July 20th, 2012. The ORP3 conference series was founded in 2001 from the EURO Association of European Operational Research Societies. It is financed by the EURO association and it is an event for Ph.D. students and young post-docs to present their work and discuss their research activities with other young researchers and outstanding scholars in the field of operations research. The conference has no specific topics or themes. The earlier conferences were located in Paris, France (2001); Lambrecht, Germany (2003); Valencia, Spain (2005); Guimaraes, Portugal (2007); and Cadiz, Spain (2011). In Linz there were 32 participants from 17 different countries. The following nine papers are expanded versions of a selection of the best papers presented during the conference. Two are survey papers and seven are regular papers.