On behalf of the Organizing Committee and the International Advisory Board we would like to invite you to participate in OP2017 to be held in Québec City, Canada, 19-23 June 2017. The Optical Probes Conference is the premier series of meetings in the field of photophysics of organic semiconductors, and its scope now extends to cover hybrid semiconductor such as perovskites amongst others. The previous conferences took place at Snowbird (1992), Salt Lake City (1994), San-Diego (1997), Salt Lake City (2000), Venice (2003), Bangalore (2005), Turku (2007), Beijing (2009), Santa Fe (2011), Durham UK (2013), and Hong Kong (2015). The scope of the current conference is a variety of excited state phenomena in technologically important materials and biosystems, including size-dependent and time-dependent electronic interactions, excited state dynamics, strong light-matter interactions, quantum confinement, photocarrier transport, and novel spectroscopic techniques. Our objective is to place central emphasis on the generality of the phenomena rather than specifics of the systems and optical measurement.