This experimental research investigates the nature and the causes of the errors made by Italian university students in the oral production of French. First, the method used to create the corpus is described. Secondly, it is illustrated the analysis grid that was designed according to the Jamet model on the basis of psycholinguistic and language teaching research in the second half of the twentieth century. The grid is a tool for collecting and describing errors in the oral production, enabling us to identify their causes, out of an evaluation context. At the linguistic level, the results show that lexical errors are dominant followed by syntactical, morphological and phonetic errors. At the pragmatic level, in most cases the communication is possible even if words are incorrect. Concerning the sources of mistakes, it was found that errors due to the interference (transfer of the mother tongue) are more frequent than errors caused by the interlanguage (evolutionary errors). Error analysis currently receives a renewed attention in the light of advances in psycholinguistics and language teaching. The understanding of errors in their nature and in their psycholinguistic mechanisms can lead researchers, teachers and students in their activities. Researchers can find answers for questions about the relationship between native language and learning language; teachers are involved with the question of adopting the best reaction to errors; students can be led to develop their metacognitive competences.