Concurrency has been a popular topic in the programming community in the last decade and has received special attention in the Ruby community in recent years. José Valim will start his talk by explaining why concurrency has become so important and why it is particularly hard to write safe concurrent software in Ruby, based on his experience from working on Ruby on Rails. The goal of this talk is to highlight the current limitations and start the search for possible solutions, looking at how other languages are tackling this issue today.