This study investigated the current state of writing instruction in science classes (Grades 6-12). A random sample of certified science teachers from the United States (N = 287) was electronically surveyed. Participants reported on their purposes for teaching writing, the writing assignments most often given to students, use of evidence-based writing practices, and the instructional adaptations made for struggling writers in science class. Typical practice was examined against a theoretical framework for disciplinary writing in science that articulates research-based and evidence-based practices to improve writing and learning outcomes for all students, including struggling writers. Descriptive results, exploratory factor analysis, and examination of differences between groups (middle school and high school teachers) revealed concerns about the quantity and quality of writing practices in secondary science classrooms, especially at the high school level. Although the majority of participants report to include writing purposely to accompany the inquiry process, most of the writing tasks teachers report to include in science require minimal composition. Participants report to include evidence-based practices for teaching writing and adapting instruction to support struggling writers at a frequency range of once per year to once per quarter. Results inform recommendations for teacher education, professional development, and instructional reform for disciplinary writing in science that supports all learners.