Symposium JJ on "Intermetallics-Based Alloys: Science, Technology and Applications," held November 26th through November 28th at the 2012 MRS Fall Meeting in Boston, Massachusetts, was the fifteenth in a series of symposia on intermetallic phases held every two years at the MRS Fall Meetings. It encompassed six oral sessions and one poster session, attracted about 150 participants from all over the world, and made it one of the best attended regular meetings on intermetallic phases. This symposium focused on new understanding and developments within the realm of microstructure, processing, and properties of intermetallic compounds and multiphase alloys where intermetallic compounds are the major constituents. This volume gives a representative overview of the current state of research on intermetallic phases, providing an insight into the current state of development of individual intermetallic alloy systems and identifying areas for future research.