The French language imposes an additional difficulty for gerontological research: the lack of research on valid and reliable instruments of measurement in the French language. The translation into French of instruments already developed and validated in English is an interesting solution to this problem, since it offers the opportunity of profiting from previous research and allows for international comparisons. However, translation must follow strict rules to ensure that psychometric properties of the instrument have not been altered. A consensus workshop concluded that the following steps were needed in translating from English an instrument for gerontological research: (1) selection of the most valid and reliable instrument in English; (2) translation into French and back again into English; (3) review of the translated versions by a committee; (4) pretest; (5) test-retest (and if indicated inter-rater) reliability study. An inventory of all translated instruments showed that very few instruments fulfil these basic rules. This inventory is a useful tool for researchers and will stimulate research on measurement instruments and encourage publication of its results.