Writing is a key component of practically all domains of human endeavor. Through writing, we build up social networks, develop projects, inform colleagues and customers, and generate the basis for decisions. The quality of writing is often decisive for social resonance and professional success. Nevertheless, we still lack crucial knowledge about writing processes, knowledge that would form the basis of systematic writing education in pedagogic, academic, and professional settings. Thus far, writing has been described in the research literature as an interplay of situations, strategies, and phases - with phases being identifiable temporal procedural units with typical dominant writing actions such as "formulating" or "source reading". Phases are recognized as essential for the success of writing processes. At the same time, most scientific approaches to writing base their phase concepts and phase descriptions on introspection or single case studies. The methodology for a rigorous, objectively verifiable analysis of the structure of writing processes and therefore for an empirically testable explanation of the nature and interplay of phases in writing processes has not yet been developed. This is exactly what the research project outlined here aims to do: to explore and to model writing phases based on statistical methodology and thus to provide a solid foundation for good practice models of writing processes - a conditio sine qua no for systematic education in writing. The research project is based on one of the most extensive data collections of writing processes in natural settings. The data are available in a so-called time series format which allows the use of particular statistical techniques beyond those normally associated with corpus linguistics. The dynamics of writing activities such as insertions or deletions can be analyzed and related to background conditions such as the writing task and the experience of the writers. Expected results will allow us a) to deduce empirically- and theoretically-based models of good practice in writing processes in specific settings and therefore b) to systematically evaluate competence and progress in (professional) writing. Both a) and b) are the conditiones sine qua non for the design of systematic writing courses, training and coaching. Practical deliverables of the project will include task- and domain-specific good practice models of writing processes.