A follow-up booklet contains assessment information the purpose of which is to enable the subsequent teacher to identify the pupil's level in order to follow a course of training consistently. ls this information a faithful and valid representation of the skills actually gained by the pupil? The article presents the results of a comparative experiment of two assessment and follow-up documents featuring different approaches learning : the criteria grid and the learning portfolio. The experiment concentrates on evaluating learning to read. The same protocol was suggested to teachers from three different educational systems. Results show that if the grid is best suited for the «good» pupil, the grid seems to be unsuitable method, or even detrimental, for the pupil said to be «experiencing difficulties». The learning portfolio is more faithful and does not depend so much on the pupil's level. Nevertheless, its optimum use requests, in addition to the records of the pupil's works, synthetical information giving a general overview of the pupil's skills.