This book constitutes the refereed proceedings of the 6th International Symposium on Leveraging Applications of Formal Methods, Verification, and Validation, ISoLA 2014, held in Corfu, Greece, in October 2014, and the 5th International Symposium, ISoLA 2012, held in Heraklion, Crete, Greece, in October 2012. The 9 revised full papers presented were carefully reviewed and selected from 22 submissions. This volume combines the post-conference proceedings of the 2014 Doctoral Symposium and the 2014 Tutorial "Automata Learning in Practice" with the post-conference publication of selected contributions from the Tracks "Process-Oriented Geoinformation Systems and Applications" and "Processes and Data Integration in the Networked Healthcare" of ISoLA 2012.