While running TestRunner, i noticed this: LinkedListTest>>testTAdd does an infinite loop. This is because: self collection first == self element since the test does: self collection add: self element this results in: self collection firstLink next next == firstLink and consequently any loop will loop infinitely... My base image is not well equipped with a Trait-aware Browser, so i let this one to Trait experts. Anyway, I find LinkedList is NOT a generic Collection but rather a single not reusable hack for Process. This is regularly bugging newcomers, and I would recommend an evolution toward something like http://lists.squeakfoundation.org/pipermail/beginners/2008-July/004835.html That is, Link should be a transparent-implementation-defined-intermediate not visible via standard add:/remove:/do: messages. User should not have to provide a Link, but only the value. Only LinkedList specialized messages like addLink: removeLink: linksDo: should deal with user provided Link for more advanced features. Think of Dictionary and Association. A user can use Dictionary with: at: / at:put: without knowing about Association. Nicolas