The European Concerted Action Research Programs began in 1971. COST 501, which concentrates on materials problems in gas turbines, coal combustion and gasification, and diesel engines, is now entering its third round. The work package concept of the technical program is introduced and highlights of the second round are described. COST 501 provides a good illustration of what can be achieved in long-term collaborative research with realistic technical targets that are periodically defined by the industries involved.