Developing writers make qualitative changes in their written products as they progress from scribbling and drawing to conventional, paragraph level writing. As yet, a comprehensive measurement tool does not exist that captures the linguistic and communicative changes (not just emergent spelling) in the early stages of this progression. The Developmental Writing Scale (DWS) for beginning writers was developed as a tool that can capture evidence of refined changes in growth over time. This measure is a 14-point ordinal scale that defines qualitative advances in levels of a learning progression for beginning writing from scribbling to cohesive (linguistically connected) and coherent (on an identifiable topic) paragraph-level writing. The measure can be used with young typically developing children and children with disabilities at all ages who are functioning at beginning levels of writing. Limitations of current writing measures, in contrast to the DWS, are described. The development of the DWS and techniques for using the measure are described with regard to construct and content validity. Preliminary research on reliability of DWS scoring and validity for 5 purposes support usefulness of the DWS for educational and research purposes, including monitoring the progress of beginning writers with significant disabilities.