The series of workshops on {\it New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments} was initiated with the\break ATHOS 2012 meeting, which took place in Camogli, Italy, June 20--22, 2012. It was followed by ATHOS~2013 in Kloster Seeon near Munich, Germany, May 21--24, 2013. The third, ATHOS3, meeting is planned for April 13--17, 2015 at The George Washington University Virginia Science and Technology Campus, USA. The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the INT-JLab Workshop on Hadron Spectroscopy in Seattle in 2009, the International Workshop on Amplitude A...