The translation or the adaptation of tests, which take into account cultural and linguistic diversity, is more and more frequent. Different factors explain this situation, such as economic imperatives or the complexity of creating a new test. It is necessary to make sure that these translation or adaptation procedures take place according to a rigorous method which takes into account main threats to validity. Indeed, the test developers must make sure to reduce as much as possible the biases which could affect various subgroups of the population. This paper presents some pitfalls that can affect test validity when test developers have to translate or adapt items.