Use IntelliJ IDEA X EAP (http://confluence.jetbrains.net/display/IDEADEV/IDEA+X+EAP) a Scala Plugin nightly build (http://confluence.jetbrains.net/display/SCA/Scala+Plugin+Nightly+Builds+for+IDEA+X) The following steps are required to use IntelliJ IDEA on Scala trunk - Copy the *.iml.SAMPLE / *.ipr.SAMPLE files to *.iml / *.ipr - In IDEA, create a global library named "ant" which contains "ant.jar" - In the Scala Facet of the "library" module, update the path in the command-line argument for "-sourcepath" - In the Project Settings, update the "Version Control" to match your checkout Known problems - Currently, it's not possible to build the "actors" module in IDEA