The European Lisp Symposium is an annual conference devoted to the Lisp programming language family. All Lisps are welcome. The 2018 edition of the symposium has been announced and is being planned. It will be held in Marbella, Spain, on the sunny southern Mediterranean coast, on April 16 and 17 (Monday and Tuesday).
If you're able to come, I encourage you to submit a presentation or contribute a lightning talk.
I myself was at the 2010 edition of the European Lisp Symposium, held in Lisbon, Portugal. At the time, I was still very much a Common Lisper. These days, I work more with Racket, as you may guess by browsing the articles and tutorials here. Looking back at the 2010 conference program, I am surprised to see that the father of Racket, Matthias Felleisen, was one of the keynote speakers.