Through the use of multiple early writing assessments and a theoretically aligned refined coding system, this study examined preschool children's early writing skills. A total of 496 preschool-aged (3- to 5-year-old) children were assessed on writing tasks designed to measure their handwriting, spelling, writing concept, and composing skills. Multiple structural equation models were employed to examine how the writing tasks used to elicit children's writing and the refined scoring rubrics worked together to capture children's early writing skills. The final multitrait multimethod (MTMM) model indicated that preschool writing tasks suggested three distinct underlying skills, namely handwriting (containing handwriting and writing concept indicators), spelling, and composing. It also confirmed that the early writing skills elicited by the four early writing tasks (e.g., name, letter, word, and story writing) were distinguishable from each other. This suggests that these early writing tasks provide unique information about children's writing and can be used for different assessment purposes. The results also suggest that the refined coding system and the four early writing tasks appear to be reliable and valid measures of preschool early writing. Findings have implications for the teaching and assessment of preschool early writing.