Writing is a key area of literacy in the early years, however writing receives less research attention than reading despite its impact on students' learning generally, and literacy development specifically. Writing skills have also been shown to be quite stable--good writers in the early years stay good writers in the later years. Therefore it is critical to better understand the aspects of writing central to development that might support teaching and learning. In this paper we share findings from the analysis of 500 writing samples from 250 students. The students were in Year 1, which is the second year of school in New South Wales and Victoria, Australia. Samples were collected at two points in time (approximately four to five months apart) and analysed using a writing analysis tool developed by the authors in an earlier stage of the study. The results reported and discussed here show levels of attainment and changes in students' writing in the areas of text structure, sentence structure, vocabulary, spelling, punctuation and handwriting, and also highlight relationships between these dimensions as students develop increasing control over writing. Socio-educational advantage, gender differences, and findings specific to children who learn English as an additional language are also reported. The findings have implications for practice in the early years of schooling. They also offer a conceptualisation of students' early writing based on an analysis process that integrates the authorial and secretarial dimensions of writing and provides teachers with relevant data to plan instruction.