Findings from education to neuroscience highlight the role of young children's print-related skills, including early writing, in predicting and enhancing the development of their later literacy abilities. However, the field lacks standardized, comprehensive measures with relatively brief scoring systems that can capture the progression from scribble lines into shapes, letters, first words, and messages. Repeated writing samples from Tools of the Mind curriculum provided a unique opportunity to examine growth across 6 months of preschool. To score the continuum of early writing skills, we designed a pilot 9-point scale (Early Writing-9; EW-9). Inter-coder agreement was high (ICC = 0.96, p < 0.001). In a sample of 62 children (3-5-years of age), we scored an average of 16 weekly samples per child, from the beginning of the school year until early spring. Findings from multilevel growth-curve models demonstrated that the development of early writing skills was substantial, highly variable, and often rapid. The shape of the trajectory yielded significant linear, quadratic, cubic, and quartic trends, consistent with a pattern of overall tapering growth. Among all predictor variables entered, including gender, age, and number of years in the program, only name-writing ability (assessed at school entry) predicted early writing scores after 6 months. Theoretical and educational implications for early writing development during preschool are discussed.