In this paper, we put forward an approach for analyzing documents and documentary activities in various working contexts. This approach comprises five interdependent steps. The first step relies on preliminary observations of the working situation and aims to establish a pre-diagnosis: are documents and documentary activities likely to generate specific malfunctions? The following three steps are run in parallel. The first one aims to describe the existing information system precisely. The description is based on a model that is derived from the field of information science (Actors exert Activities on Sites towards Documents produced under Modalities and belonging to document Types). The second of the three parallel steps aims to categorize the documents within five dimensions, according to their thematic, informational and temporal content, author?s communicative intentions and signaling devices. With the last of the three parallel steps, documentary activities are analyzed using several cognitive models in order to understand the difficulties that actors may encounter when performing their documentary activities. Finally, the fifth step in this approach aims to identify the disturbance sources of the information system by studying its accessibility and usability and then to propose solutions. Each step is described along three dimensions: its objective, its possible theoretical foundation, and usable methods and techniques. We illustrate the approach with a study that was carried out at the French National Telephonic Supervision Center. The pre-diagnosis showed the eminent role of documentation in the supervision activity. The diversity of the documentation generated an information overload and important cognitive costs. In particular, the description of the information system revealed the existence of multiple documentary activities (receiving, transmitting, providing, cataloging, grouping, preserving, consulting, performing, producing, and re-processing). These activities were performed by most actors at the Center, on a huge fund (about ten thousand pages), made up of documents of several types (e.g. user manuals, incident forms). Precise descriptions of the documents, within the five dimensions put forward (their thematic, informational, and temporal content, sender?s communicative intentions and signaling devices), showed the multiplicity of information contained in the documents, the multi-dimensional character of the temporal structures evoked and the diversity of the senders? communicative intentions in all documents. The analysis of the operators? documentary activities, processed by means of a simulation of two documentary tasks (consulting and grouping), revealed an important inter-individual variability, partially linked to operators? expertise in the supervision activity. Finally, from the analysis, it was possible to identify a poor level of accessibility and usability of the existing information system. Solutions were proposed?in order to give operators the means to better control their documentary activities, to verify their knowledge about the information system, and to enrich their documentary activities with the aim of empowering personalized use. Finally, the paper discusses the contributions of this approach to the field of documentary ergonomics, together with suggestions for future research.