As reported at the Seventh ESV Conference, Paris, 1979, the European car manufacturers associated with the Committee of Common Market Automobile Constructors (CCMC) carried out a large program of lateral collision tests. From this data base, CCMC proceeded to develop a mobile deformable barrier (MDB) to investigate its use as a test tool. This paper describes the criteria used in MDB definition, MDB construction, and the assessment testing undertaken to date and reviews and discusses the possibilities for further harmonization of test standards.