This article describes the instruments and experimental tasks used in exploratory tests carried out by the PACTE Group. These tests were undertaken preparatory to the final experiment designed to determine the nature of Translation Competence in written translation, the first phase of a two phase project designed to investigate the Acquisition of Translation Competence in written translation. A general overview of the characteristics of the research project is given, followed by a description of the aims and objectives of the exploratory tests, the experimental tasks and the instruments used. Some conclusions resulting from these tests are presented.