Consider creating a classloader which allows dynamic adding to the search path for launching from the command line (jirb, etc). The basic use case is being able to pull in java libraries while putzing^w working in jirb without having to restart the session with w new CLASSPATH and build everything up again. It would be nice to make the classloader a nice public api as well, so that it can be used embedded See http://kessel.ilrt.bris.ac.uk/jruby/logs/2006-11-16.txt at 9:09:14 for conversation on the topic