We introduce several Eiffel classes for concurrent programming. With these classes, we con- trol the run-time concurrent activities through THREAD objects, describe their behaviors through HOST objects and express the needed cooperation through MONITOR and CONDITION objects. We regard these classes as low-level tools. High-level classes are then developed using inheritance and in- cremental design. Our classes are built on top of the Eiffel language (i.e. without modification of the compiler), so rapid and instructive experimentations are possible.