Researchers and educators use the term "emergent literacy" to refer to a broad set of skills and attitudes that serve as foundational skills for acquiring success in later reading and writing; however, models of emergent literacy have generally focused on reading and reading-related behaviors. Hence, the primary aim of this study was to articulate and evaluate a theoretical model of the components of emergent writing. Alternative models of the structure of individual and developmental differences of emergent writing and writing-related skills were examined in 372 preschool children who ranged in age from 3 to 5 years, using confirmatory factor analysis. Results from the analyses provide evidence that these emergent writing skills are best described by three correlated but distinct factors: (1) Conceptual Knowledge, (2) Procedural Knowledge, and (3) Generative Knowledge. Evidence that these three emergent writing factors show different patterns of relations to emergent literacy constructs is presented. Implications for understanding the development of writing and assessment of early writing skills are discussed.