Hi, I would like to create a single set of test cases for all individuals in a generation, and still be able to use multithreaded evaluation. Is it possible to do this in an elegant manner? If I use "prepareToEvaluate" then it will be called for each Problem instance that is cloned, i.e. once for each thread, and as my test cases are probabilistically selected I will end up with a different set of tests cases for each thread, which I don't want! Any help appreciated, Thanks David -- David R White PhD Student Dept of Computer Science University of York, UK.