This study examines the relationship between students' demographic background and their experiences with writing at school, the alignment between state and National Assessment of Educational Progress (NAEP) direct writing assessments, and students' NAEP writing performance. The study utilizes primary data collection via content analysis of writing assessment prompts and rubrics and secondary analysis with NAEP data through hierarchical linear modeling. Results indicate students from states with writing tests more similar to the NAEP do not perform significantly better than students from states with writing tests less similar to the NAEP. Rather, student demographic characteristics, including gender, ethnicity, SES, disability status, and English learner status significantly predict NAEP writing performance, as do factors related to frequency of writing across subject areas, frequency of writing for varied purposes, frequency of writing process use, and computer use in writing. The implications of the findings for writing instruction are discussed.